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Subelement A
General
Section A
SITOR-ARQ is a common mode of data communications in the maritime service. It is a system based on transmission bursts and acknowledgements. What is the baud, and interval between the burst transmissions:
  • Correct Answer
    100 baud, 240 ms interval
  • 50 baud, 1000 �s interval
  • 200 baud, 10 ms interval
  • None of the above

SITOR-ARQ is a common mode of data communications in the maritime service. It is a system based on transmission bursts and acknowledgements. What is the baud, and interval between the burst transmissions:

(A). 100 baud, 240 ms interval

For info, see Wavecome site's article on WAVECOM Decoder Online Help 10.2.0 SITOR-ARQ

For data burst calculation, please see CCIR 476-4 / CCIR 625 Mode A (aka SITOR ARQ / AMTOR)

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Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:
  • Lines-per-inch (LPI), and primary scan direction (PSD)
  • Frequency shift (FS), and phase response pattern (PRP)
  • Black-mode signal (BMS), and frequency jitter tolerance (FJT)
  • Correct Answer
    Index of cooperation (IOC), and revolutions per minute (RPM)

Weather information is commonly sent by radio in map form by one-way facsimile transmission. Two common parameters which must be set by the receiving station are:

(D). Index of cooperation (IOC), and revolutions per minute (RPM)

For radiofax, in radio waves SSB mode, sends by radio weather map pictures and information. To translate the radio waves into pictures, in terms of the number of lines, characters per line between the sending machine and the receiving printer, the numerical data was transmitted, known as the index of cooperation (IOC) must known.

Since the radio fax machines used drum readers, the revolutions per minute (RPM) had to be know.

For more info, please see Wikipedia's article on Radiofax.

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2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:
  • Correct Answer
    Solely intended for distress and safety communications
  • Built and sold after the GMDSS implementation date
  • Built and sold before the GMDSS implementation date
  • Solely intended for ship-to-shore public correspondence

2182 kHz is the international radiotelephone distress frequency. It is also used for a calling channel. The authorized mode of emission is H3E (single-sideband full carrier). A3E (double-sideband full carrier) is only authorized for equipment:

(A). Solely intended for distress and safety communications

2182 kHz is Medium Frequency (MF) equivalent of VHF Channel 16. Frequencies in this range typically provide longer range communications.


Code of Federal Regulations, Title 47 Chapter I Subchapter D Part 80 Subpart H Radiotelephony

§ 80.369 Distress, urgency, safety, call and reply frequencies.

47 CFR 80.369(a) In the 1605-3500 kHz band, the frequency 2182 kHz is an international radiotelephony distress, urgency and safety frequency for ship stations, public and private coast stations, and survival craft stations.

It is also used for call and reply by ship stations on a primary basis and by public coast stations on a secondary basis.

The carrier frequency 2191 kHz may be used as a supplementary calling frequency in areas of heavy usage of 2182 kHz .

All stations must use J3E emission when operating on 2182 kHz and 2191 kHz, except that:

47 CFR 80.369(a)(1) H3E emission may be used on 2182 kHz for communications with foreign coast and ship stations; or,

47 CFR 80.369(a)(2) A3E emission may be used on 2182 kHz by portable survival craft stations, or transmitters authorized for use prior to January 1, 1972.

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Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:
  • Approx 67 volts for a normal balanced system with no faults
  • 0 VAC for a system with that phase faulted to ground
  • 120 VAC when another phase is faulted to ground
  • Correct Answer
    Any of the above

Ship's power is generated as 3-phase and is ungrounded. On a delta-wound transformer with 120 VAC line-to-line secondary, what is the voltmeter reading from line to ground:

(D). Any of the above

  • Approx 67 volts for a normal balanced system with no faults

  • VAC for a system with that phase faulted to ground

  • 120 VAC when another phase is faulted to ground

The 3-phase current has three sine waves. The currents are at different angles, with L1 at +120 degrees, L2 at 0 degrees, and L3 at -120 degrees. This is needed to power large electric motors.

When you measure voltage between L2 and either L1 or L3, you will get 120 VAC (volt alternating current).

If there is a short (fault) or an abnormal sine wave combination, resulting from a sine wave current coming in contact with ground.

When 3 sine waves work symmetrically, in a coordinated sequence, then they are balanced. When not experiencing a short (or ground connection), then volt measurement reflects the difference between volt levels (voltage is an expression of the difference of electron pressure between two connections)

The Delta configuration uses 3 wires for the 3 sine waves, with no 4th wire, which would have been the neutral ground wire.

For info on electric phase power generation and distribution, please see Wikipedia's article on Three-phase electric power

For info on electric short circuit faults, please see Wikipedia's article on Electrical fault

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When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?
  • Lightning arresters and suppressors
  • Protection diodes on receiver input
  • Capacitive coupling and static dissipative circuits
  • Correct Answer
    Any combination of the above

When passing through areas of static charge, high voltages can accumulate on antennas which are insulated from ground. What protects a connected receiver from damage?

(D). Any combination of the above

  • Lightning arresters and suppressors
  • Protection diodes on receiver input
  • Capacitive coupling and static dissipative circuits

Static charge occurs when there is a difference between negative and positive number of electrons. Electrons flow from negative (toward) to positive (back) connections.

If the flow is interfered with or stopped, then an accumulation of the negative electrons occurs, which is the static electricity (static=> not moving). Thus, electrons can accumulate on antennas, and discharge on the radio receivers.

To prevent sudden electron transfer, like a short spark when you touch something that was rubbed appropriately, items that can absorb the sudden release of electrons protect the radio receiver.

Capacitive coupling is a capacitor that would absorb the release of stored electrons. Diodes control the flow of electrons.

For more info, please see Wikipedia's article on Static Electricity.

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Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?
  • Provides aerodynamic compensation for stress during high winds
  • Correct Answer
    Permits a physically short antenna to appear electrically longer
  • Improves the near-field radiated pattern at the expense of the far-field pattern
  • Prevents salt build-up on antennas from shunting RF energy to ground

Vertical shipboard antennas for use in the MF band (410-525 kHz) are often fitted with top-hat loading sections. What is the purpose of these structures?

(B). Permits a physically short antenna to appear electrically longer

The top-hat or T-antenna, is a horizontal wire (akin to the Beverage antenna), suspended between to poles, with a third wire connected at the center of the horizontal wire and connected to the transmitter/receiver, kind of like the dipole antenna.

The receiving waves flow from the horizontal wire to the vertical center wire to the receiver. Transmissions flow from the center wire to the both sides of the horizontal wire.

A vertical wire is connected to the center of the horizontal wires and hangs down close to the ground, connected to the transmitter or receiver.

Combined, the two sections form a ‘T’ shape, hence the name. The transmitter power is applied, or the receiver is connected, between the bottom of the vertical wire and a ground connection.

T-antenna is easily installed ships between masts and vertical center line connected to the trans/receiver. (Even Titanic used this configuration and sended out the distress signal.)

To extend the wavelength of a shorter antenna, it should be mounted as high as possible, as mathematically its height is squared for effective receiving or transmitting.

For more info, please see Wikipedia's article on T-Antenna.

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Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:
  • Antenna must be grounded to suppress spurious side-lobes
  • Correct Answer
    Modulation must be reduced to zero to eliminate sidebands
  • Voltage to the PA must be kept at half-value
  • Antenna current must be reduced to about 2.5 uA

Modern reserve transmitters are solid-state designs and transmit using only A2 modulation. When measuring transmitter center frequency, what precaution must be taken:

(B). Modulation must be reduced to zero to eliminate sidebands

This modulation can be thought of as the Double Sideband Suppressed Carrier Modulation (DSBSC). Thus, data is sent by modulating the carrier frequency itself. The AM radio can easily pick up these continuous wave propagations.

Because all of the transmitted power (volts x amperes=watts), is concentrated on the carrier frequency, without being dispersed on upper or lower sidebands. Thus, it can carry the signal much farther.

For more info, please see Wikipedia's article on Types of radio emissions and Continuous wave

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Voltage may be expressed by what other expression?
  • Difference of potential
  • IF drop
  • Electromotive force
  • Correct Answer
    All of the above

Voltage may be expressed by what other expression?

(D). All of the above

  • Difference of potential
  • IF drop
  • Electromotive force

Because the difference in the number of electrons between two items, when they are connected there is a waterfall like flow of electrons. The amount of rushing electrons to the low electrons area is called the volt amount.

It can be thought of as the pressure of the flow of electrons due to the difference in potential (amount of electrons).

If you multiply the amount of electrons, or the current (ampers) by the amount of resistance that a medium through which electrons flow (silver, copper, not glass), then you will get the amount of voltage (pressure on the amount of electrons to move).

Voltage as IF drop may refer to the (I) as symbol for current (ampers) and (F) as factor or force. More on Voltage drop on Wikipedia's article Voltage drop

For Voltage info, see Electrical 4 U site article What is Voltage? and Wikipedia's article Voltage

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Amperage may also be known by:
  • Electron flow
  • Electron drift
  • Electric current flow
  • Correct Answer
    All of the above

Amperage may also be known by:

(D). All of the above

  • Electron flow
  • Electron drift
  • Electric current flow

In simplest terms, it is the amount of electrons flowing through the skin of the conduit (gold, silver, iron, copper). Electrons travel on the surface of the conduits. This called the current, and is measured in amperes.

Voltage is what pushes amperes to flow through the conduit which offers some resistance, measured in ohms.

For more info, see Wikipedia's article on Amperes

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Factors which determine the amplitude of the voltage induced in a conductor which is cutting magnetic lines of force:
  • Flux density
  • Velocity that the conductor cuts the magnetic lines of force
  • The angle at which the conductor cuts through the magnetic lines of force
  • Correct Answer
    All of the above

Factors which determine the amplitude of the voltage induced in a conductor which is cutting magnetic lines of force:

(D). All of the above

  • Flux density

  • Velocity that the conductor cuts the magnetic lines of force

  • The angle at which the conductor cuts through the magnetic lines of force

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An electrical potential may be generated by:
  • Varying a magnetic field through a circuit
  • Chemical action
  • Photo-electric action
  • Correct Answer
    All of the above

An electrical potential may be generated by:

(D). All of the above

  • Varying a magnetic field through a circuit
  • Chemical action
  • Photoelectric action

The potential refers to the energy that can be concentrated by various methods.

For more info, please see Wikipedia's article on Electric Potential

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Ohm's law is stated as:
  • E = IR
  • I = E / R
  • R = E / I
  • Correct Answer
    All of the above

Ohm's law is stated as:

(D). All of the above

  • E = IR    Voltage = Current x Resistance
  • I = E / R    Current = Voltage / Resistance
  • R = E / I    Resistance = Voltage / Current

For more info, please see Wikipedia's article on Ohm's law

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The unit of electrical power is:
  • Watt
  • Joule per second
  • Correct Answer
    Both A & B
  • None of the above

The unit of electrical power is:

(C). Both A & B

  • Watt
  • Joule per second

Electric power is the amount of energy transferred through the conduit, and is measured in watts, which is Joules per second. It can be thought of as the amount of power, which reflects the "work done" per second. The "work done" is also called Joule unit.

For more info, please see Wikipedia's article on Electric power

Also, see article Is one joule per second equivalent to one watt?

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The unit of conductance is:
  • Ohm
  • Correct Answer
    Mho
  • Henry
  • Ampere

The unit of conductance is:

(B). Mho

Conductance is the opposite of resistance. The resistance is measured in Ohms, but conductance is measured in Mho's. The Mho, is the 1/ohm, that is the Mho is the reciprocal of Ohm.

For more info, please see ElectronicNotes' site article Electrical Conductivity: mho, siemens

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The unit of inductance is:
  • Correct Answer
    Henry
  • Joule
  • Coulomb
  • Ohm

The unit of inductance is:

(A). Henry

The inductance is the magnetic field caused by the flow of current, and this field works like resistance to the current flow. The unit of inductance, Henry, refers to Joseph Henry who discovered inductance.

For more info, see Wikipedia's article Inductance Also, see article on Joseph Henry

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The ratio of current through a conductor to the voltage which produces it is:
  • Inductance
  • Correct Answer
    Conductance
  • Resistance
  • None of the above

The ratio of current through a conductor to the voltage which produces it is:

(B). Conductance

It measures how well electricity flows through the skin of the substance such as silver, gold, copper, iron, etc.

For more info, see Electrical4U site, article Conductance: What is it? (Definition, Units & Formula)

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The product of the number of turns and the current in amperes used to describe relative magnitude is:
  • Correct Answer
    Ampere turns
  • Joules per second
  • Push-pull convergence
  • Dissipation collection

The product of the number of turns and the current in amperes used to describe relative magnitude is:

(A). Ampere turns

When you run electric current through wires that were wound in a circular pattern, you get a magnetic field that is strong. In fact, whenever you run current, there is a magnetic field. In the coil, the field is strong because the field goes through the center of the coil.

The more turns in the coil, then there is more magnetic field created.

For more info, see Wikipedia's article Electromagnetic coil
and Tesla Scientific site's Ampere-Turn Calculator

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The property of a conductor or coil which causes a voltage to be developed across its terminals when the number of magnetic lines of force in the circuit or coil is changed is:
  • Capacitance
  • Correct Answer
    Inductance
  • Conductance
  • None of the above

The property of a conductor or coil which causes a voltage to be developed across its terminals when the number of magnetic lines of force in the circuit or coil is changed is:

(B). Inductance

The inductance is the magnetic field caused by the flow of current, and this field works like resistance to the current flow. The unit of inductance, Henry, refers to Joseph Henry who discovered inductance.

For more info, see Wikipedia's article [Inductance][1] Also, see article on [Joseph Henry][2]

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The charge of electricity which passes a given point in one second when a current of one ampere is flowing is:
  • Correct Answer
    Coulomb
  • Joule
  • Watt
  • None of the above

The charge of electricity which passes a given point in one second when a current of one ampere is flowing is:

(A). Coulomb

Coulomb has been adopted as the internationally recognized amount of electric charge, which is the amount of amperes (electrons flowing) per second.

For more info, see Wikipedia's article on Coulomb

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C = capacity in farads. Q = the measure of the quantity of charge of electricity in Coulombs. E = the applied voltage. So Q = CE:
  • Correct Answer
    Determines the quantity of charge in a capacitor
  • Determines the Q of a circuit
  • Both A & B
  • None of the above

C = capacity in farads.
Q = the measure of the quantity of charge of electricity in Coulombs.
E = the applied voltage.
So Q = CE:

(A) Determines the quantity of charge in a capacitor

Coulomb or amount of amperes =
Farads (ability to store electricity) x
Voltage (the amount of difference between two unit's charges or the amount of force pushing of electrons from a unit to another)

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Resistance is:
  • The quantity which determines power loss or dissipation
  • The factor of proportionality between voltage and current
  • Measured in ohms
  • Correct Answer
    All of the above

Resistance is:

(D). All of the above

  • The quantity which determines power loss or dissipation
  • The factor of proportionality between voltage and current
  • Measured in ohms

The amount of resistance (in Ohms) that the electrons (in Amperes) experience when are pushed through a conductor by Voltage pressure.

For more info, see Fluke's site article on What is resistance?
and Wikipedia's article on Electrical resistance and conductance

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The unit of AC impedance in a circuit is:
  • Correct Answer
    Ohm
  • Mho
  • Joule
  • None of the above

The unit of AC impedance in a circuit is:

(A). Ohm

  • The quantity which determines power loss or dissipation
  • The factor of proportionality between voltage and current
  • Measured in ohms

The amount of resistance (in Ohms) that the electrons (in Amperes) experience when are pushed through a conductor by Voltage pressure.

In AC current, the resistance changes the shape of the electrical wave (sinusoidal waveform)

For more details, see Electronic Tutorials' site article AC Resistance and Impedance

For more info, see Fluke's site article on What is resistance?
and Wikipedia's article on Electrical resistance and conductance

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The unit of capacitance is:
  • Farad
  • Microfarad
  • Coulomb
  • Correct Answer
    A & B

The unit of capacitance is:

(D). A & B

  • Farad
  • Microfarad

Ability to store electrons (amperes) in a medium is measured by Farad units. Capacitors are used to store electric charges. Since a unit of Farad has a substantial charge, for smaller charges a microfarad unit is used to measure.

For more info, see Fluke's article on What is capacitance?
and Wikipedia's article on Capacitance

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Decibel is:
  • The unit used to express the ratio between two sound power levels
  • The unit used to express the ratio between two electrical power levels
  • Correct Answer
    Both A & B
  • None of the above

Decibel is:

(C). Both A & B

  • The unit used to express the ratio between two sound power levels

  • The unit used to express the ratio between two electrical power levels

Basically, the amount of push on air, air pressure, is measured in decibels. Decibels increase in logarithmic units, not arithmetical units.

For more info, see Physclips' article on dB: What is a decibel?
and Wikipedia's article on Decibel

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What factors determine the charge stored in a capacitor?
  • Capacitance of the capacitor
  • The applied voltage
  • Correct Answer
    Both A & B
  • None of the above

What factors determine the charge stored in a capacitor?

(C). Both A & B

  • Capacitance of the capacitor
  • The applied voltage

Capacitors store electrical charges when pressure is placed on electrons to move (applied voltage) to a capacitor.

The ability to store electrons (amperes) in a medium is measured by Farad units. Capacitors are used to store electric charges. Since a unit of Farad has a substantial charge, for smaller charges a microfarad unit is used to measure.

For more info, see Fluke's article on What is capacitance?
and Wikipedia's article on Capacitance

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Ohm's law for AC circuits when I = amperes, E = volts, Z = impedance in volts is:
  • I = E/Z
  • E = IZ
  • Z= Z/I
  • Correct Answer
    All of the above

Ohm's law for AC circuits when
I = amperes,
E = volts,
Z = impedance in volts is:

(D). All of the above

  • I = E/Z   Amperes = volts / ohms
  • E = IZ   Volts = amperes x ohms
  • Z= E/I   Ohms = volts / current

It appears that the Z=Z/I in answer C maybe simply misprint

I = E / R  Current =   Voltage / Resistance
E = IR   Voltage =  Current x Resistance
R = E / I  Resistance = Voltage / Current

For more info, please see Wikipedia's article on Ohm's law

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The formula for determining the power in a DC circuit when the voltage and resistance are known is:
  • Correct Answer
    P = ( E squared) R
  • P = EI
  • P = ( I squared) R
  • PF = W/IE

The formula for determining the power in a DC circuit when the voltage and resistance are known is:

(A). P = ( E squared) R

Power is measured in watts, or in units of Joule per second.

Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance

For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits

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The formula for finding power in a DC circuit when current and resistance are known:
  • P = IE
  • Correct Answer
    P = ( I Squared) R
  • PF = W/IE
  • None of the above

The formula for finding power in a DC circuit when current and resistance are known:

(B). P = ( I Squared) R

Power is measured in watts, or in units of Joule per second.

Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance

For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits

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The formula for finding power in a DC circuit when current and voltage are known:
  • Correct Answer
    P = EI
  • P = ( I squared ) R
  • PF = W/IE
  • None of the above

The formula for finding power in a DC circuit when current and voltage are known:

(A). P = EI

Power is measured in watts, or in units of Joule per second.

Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance

For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits

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The prefix " kilo " means:
  • Correct Answer
    To multiply by 1000 whatever quantity follows
  • To divide by 1000 whatever quantity follows
  • To add 1000 to whatever quantity follows
  • None of the above

The prefix " kilo " means:

(A). To multiply by 1000 whatever quantity follows

Kilo means a thousand, or 10 to 3rd power, or 10x10x10

For more info, see Wikipedia's article on Kilo-

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The prefix " micro " means:
  • Correct Answer
    Divide by 1,000,000 whatever quantity follows
  • Multiply by 1,000,000 whatever quantity follows
  • Add 1,000,000 to whatever quantity follows
  • Divide by 1,000 whatever quantity follows

The prefix " micro " means:

(A). Divide by 1,000,000 whatever quantity follows

Micro is a one millionth of a unit, or 10 to minus 6.
To get 10 to minus 6, move the decimal 6 positions from unit 1, or so 0.000 001

10 to minus 1 is 0.1 or deci-
10 to minus 2 is 0.01 or centi-
10 to minus 3 is 0.001 or mili-

For more info, please see Wikipedia's article on Micro-

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The factor by which the product of volts and amperes must be multiplied to obtain true power is:
  • Correct Answer
    Power factor
  • Apparent power
  • Phase angle
  • None of the above

The factor by which the product of volts and amperes must be multiplied to obtain true power is:

(A). Power factor

Power is measured in watts, or in units of Joule per second.

Watts = Amperes x Voltage or
Watts = (Amperes)2 x Resistance or
Watts = (Voltage)2 / Resistance

For more info, see Electrical Technology site's article on Power Formulas in DC and AC Single-Phase & Three-Phase Circuits

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The prefix " meg " means:
  • Correct Answer
    Multiply by 1,000,000 whatever quantity follows
  • Multiply by 100,000 whatever quantity follows
  • Multiply by 1,000 whatever quantity follows
  • Divide by 1,000,000 whatever quantity follows

The prefix " meg " means:

(A). Multiply by 1,000,000 whatever quantity follows

Mega is the unit multiplied by 10 to 6th power. (10)6, which is 10x10x10x10x10x10 = 1,000, 000

For more info, see Wikipedia's article on Mega-

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Factors which influence the resistance of a conductor:
  • Cross-sectional area
  • Length
  • Temperature
  • Correct Answer
    All of the above

Factors which influence the resistance of a conductor:

(D). All of the above

  • Cross-sectional area
  • Length
  • Temperature

The resistance of a conductor is affected by:

  • the amount of cross-section area in inverse proportion
  • the length of a conductor in direct proportion
  • most conductors, not all, increase resistance as the temperature goes up
  • type of conductor material.

For more information, see Engineering Educators site article on Factors Affecting Resistance

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Halving the cross-sectional area of a conductor will:
  • Correct Answer
    Double the resistance
  • Half the resistance
  • Not affect the resistance
  • None of the above

Halving the cross-sectional area of a conductor will:

(A). Double the resistance

The resistance of a conductor is affected by:

  • the amount of cross-section area in inverse proportion
  • the length of a conductor in direct proportion
  • most conductors, not all, increase resistance as the temperature goes up
  • type of conductor material.

For more information, see Engineering Educators site article on Factors Affecting Resistance

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Name four conducting materials in order of their conductivity.
  • Gold, silver, copper, platinum
  • Correct Answer
    Silver, gold, zinc, platinum
  • Silver, copper, zinc, aluminum
  • Aluminum, zinc, copper, platinum

Name four conducting materials in order of their conductivity.

(B). Silver, gold, zinc, platinum

For more information, see Engineering Educators site article on Factors Affecting Resistance the "Figure 41. Resistivity table," for measurements of resistivity.

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Good insulators at radio frequencies are:
  • Pyrex, mica
  • Isolantite, steatite, polyethylene
  • Rubber, porcelain
  • Correct Answer
    A & B

Good insulators at radio frequencies are

(D). A & B

  • Pyrex, mica
  • Isolantite, steatite, polyethylene

What makes a good insulator is not just lack of conductivity, but also the effect of sunlight, especially ultraviolet waves (being highly energetic) they degrade the insulating material.

Well illustrated info on ThoughtCo article 10 Examples of Electrical Conductors and Insulators Things That Don't Conduct Electricity and Things That Do

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A resistance across which a constant voltage is applied is doubled. What power dissipation will result?
  • Correct Answer
    One half
  • One fourth
  • Doubled
  • None of the above

A resistance across which a constant voltage is applied is doubled. What power dissipation will result?

(A). One half

The resistance of a conductor is affected by:

  • the amount of cross-section area in inverse proportion
    So, if you double the resistance, the loss of energy will be the reciprocal, or 1 over double (1/2), or one-half.
  • the length of a conductor in direct proportion
  • most conductors, not all, increase resistance as the temperature goes up
  • type of conductor material.

For more information, see Engineering Educators site article on Factors Affecting Resistance

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The needle of a magnetic compass when placed within a coil carrying an electric current:
  • Will tend to become parallel with the axis of the coil
  • Will point to the north pole end of the coil
  • Will point to the south pole end of the coil
  • Correct Answer
    A & B

The needle of a magnetic compass when placed within a coil carrying an electric current:

(D). A & B

  • Will tend to become parallel with the axis of the coil
  • Will point to the north pole end of the coil

For more details, please see Siyavula Technology-Powered Learning site, article on 10.2 Magnetic field associated with a current

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Electrical resistance is measured with:
  • Correct Answer
    An ohmmeter
  • A wattmeter
  • An Ammeter
  • A voltmeter

Electrical resistance is measured with:

(A). An ohmmeter

The meter measures how much a substance prevents the flow of electrons (current) through its surface skin, known as the electrical resistance, and expressed in ohm units.

For more info, see Elprocus site, for article on What is an Ohmmeter? Circuit Diagram, Types and Applications

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The sum of all voltage drops around a simple DC circuit, including the source, is:
  • Correct Answer
    Zero
  • Insignificant
  • Infinite
  • None of the above

The sum of all voltage drops around a simple DC circuit, including the source, is:

(A). Zero

That is just the definition of changes in voltage in a simple DC circuit. This called the Kirchhoffs' Voltage Law, or the Law of Conservation of Energy.

The law declares that:

"'in any closed loop network, the total voltage around the loop is equal to the sum of all the voltage drops within the same loop.'”

This means that if you sum all the volts in the components, the sum will be zero.

For more info, see Electronics Tutorials site, article on Kirchhoffs Circuit Law

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If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
  • Correct Answer
    Doubled
  • Halved
  • Tripled
  • Same

If a resistance to which a constant voltage is applied is halved, what power dissipation will result?

(A). Doubled

The resistance of a conductor is affected by:

  • the amount of cross-section area in inverse proportion
    So, if you half the resistance, the loss of energy will be the reciprocal, or 1x2 over 1 (2/1), or double.
  • the length of a conductor in direct proportion
  • most conductors, not all, increase resistance as the temperature goes up
  • type of conductor material.

For more information, see Engineering Educators site article on Factors Affecting Resistance

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The diameter of a conductor six inches long is doubled, what will be the effect on the resistance?
  • One-fourth the original value
  • One-half the original value
  • The resistance varies inversely with the cross-sectional area of the conductor
  • Correct Answer
    A & C

The diameter of a conductor six inches long is doubled, what will be the effect on the resistance?

(D). A & C

  • One-fourth the original value

  • The resistance varies inversely with the cross-sectional area of the conductor

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A minute subdivision of matter having the smallest known unit of negative electrical charge is:
  • Correct Answer
    Electron
  • Ion
  • Gilbert
  • Joule

A minute subdivision of matter having the smallest known unit of negative electrical charge is:

(A). Electron

If you have more negative electrons than positive protons, then you have a negative electric charge.

For more info, please see Wikipedia's articles on Electron and Electric charge

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Conductors differ from nonconductors, i.e.:
  • There are a large number of free electrons in a good conductor
  • There is a small number of free electrons in a non-conductor
  • There is an equal amount of free electrons in a good conductor and in a non-conductor
  • Correct Answer
    A & B

Conductors differ from nonconductors, i.e.:

(D). A & B

  • There are a large number of free electrons in a good conductor

  • There is a small number of free electrons in a non-conductors stop the flow of electrons.

Conductors facilitate flow of electrons across their skin surface, while nonconductors do not allow the

Conductance is the opposite of resistance. The resistance is measured in Ohms, but conductance is measured in Mho's. The Mho, is the 1/ohm, that is the Mho is the reciprocal of Ohm.

For more info, please see ElectronicNotes' site article Electrical Conductivity: mho, siemens

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Direction of flow of DC electricity in a conductor can be determined by:
  • A magnetic compass and the left hand rule
  • A magnetic compass and the right hand rule
  • Connecting an ammeter with marked polarities in series with the circuit
  • Correct Answer
    A & C

Direction of flow of DC electricity in a conductor can be determined by:

(D). A & C

  • A magnetic compass and the left hand rule
  • Connecting an ammeter with marked polarities in series with the circuit

Direct Current occurs when electrons flow in a one direction only. Electronic circuits use mostly direct current from a battery or a direct current transformer.

More info on Wikipedia's article on Direct current


The flow of electrons in the same direction (DC current) creates a magnetic field. The magnetic field propagates clockwise around the surface skin of the conductor material. The compass needle will be affected by the magnetic field.

More info on Wikipedia's article on Magnetoresistance


By introducing a magnetic field to a flow of electrons in one direction, there will be created a force that is at 90 degrees (perpendicular) to the magnetic field and the flow of electrons.

On a graph, this force would be on the Y axis, while flow and magnetic force on the X axis. For simplicity, your thumb would be the force, while the index finger would show the magnetic force, while the middle finger would show a flow of electrons.

More info on Wikipedia's article on Magnetoresistance

There are various versions of the interaction of force, magnetic field, and current. Mostly, they are called either a left-hand or right-hand rule. These two are opposite of each other.

The left-hand rule shows the flow of current to produce motion, as in electric motors. The right-hand rule is the opposite, as it creates current, not using it, in generators of electricity.

See detailed explanation on Wikipedia's article Fleming's left-hand rule for motors


In the past, an instrument called "Galvanometer" was used to measure DC current. An improved version which did not require interrupting the electrical circuit is called an "Ammeter" It measures current in amperes.

For more info, please see Wikipedia's article on Ammeter

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The difference between electrical power and electrical energy is:
  • Electrical power is the rate of doing work by electricity
  • Electrical energy is the ability to accomplish work by electricity
  • Correct Answer
    A & B
  • None of the above

The difference between electrical power and electrical energy is:

(C). A & B

  • Electrical power is the rate of doing work by electricity
  • Electrical energy is the ability to accomplish work by electricity

Good simple definitions.

For more info, please see Wikipedia's articles on Electric power
and Electrical energy

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A positive temperature coefficient means:
  • Resistance increases as the temperature increases
  • Resistance decreases as the temperature decreases
  • Correct Answer
    Both A & B
  • None of the above

A positive temperature coefficient means:

(C). Both A & B

  • Resistance increases as the temperature increases
  • Resistance decreases as the temperature decreases

For greater insights, please see Wikipedia's article on Temperature coefficient

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A liquid which is capable of conducting electricity, but undergoes decomposition while doing so is:
  • Correct Answer
    An electrolyte
  • A ferromagnetic material under the influence of a magnetizing force
  • Equal to the ohmic resistance of the circuit
  • None of the above

A liquid which is capable of conducting electricity, but undergoes decomposition while doing so is:

(A). An electrolyte

Liquids with the ability to allow flow of current is called an electrolyte.

For more details, please see Wikipedia's article on Conductivity (electrolytic)

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The effective value of an RF current and the heating value of the current are:
  • Correct Answer
    The same
  • Effective value divided by two equals the heating value
  • Effective value multiplied by two equals the heating value
  • None of the above

The effective value of an RF current and the heating value of the current are:

(A). The same

For greater insights, please see Wikipedia's article on Temperature coefficient

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One horsepower is:
  • 746 Watts
  • Roughly 3/4 kilowatt
  • Corresponds to lifting 550 pounds at the rate of one foot per second
  • Correct Answer
    All of the above

One horsepower is:

(D). All of the above

  • 746 Watts
  • Roughly 3/4 kilowatt
  • Corresponds to lifting 550 pounds at the rate of one foot per second

The horsepower measurement reflects the amount of work done as one unit. There are several different horsepower measurement.

For more info, please see Wikipedia's article on Horsepower

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What factors determine the heat generated in a conductor?
  • It is directly proportional to the resistance
  • It is directly proportional to the square of the current
  • Correct Answer
    Both A & B
  • None of the above

What factors determine the heat generated in a conductor?

(C). Both A & B

Heat generated in a conductor is:

  • directly proportional to the resistance
  • directly proportional to the square of the current

For greater insights, please see Wikipedia's article on Temperature coefficient

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What is the ratio of peak to average value of a sine wave?
  • 1.57 to 1
  • 1 to 0.636
  • 1 to 1
  • Correct Answer
    A & B

What is the ratio of peak to average value of a sine wave?

(D). A & B

  • 1.57 to 1
  • 1 to 0.636

There are a number of formulas for calculating the avg value of sine wave for different waves. The 1.57 refers to the "half wave rectified sine wave." The "full rectified wave" is 0.637.

For more details, see Electrical Technology site, article on RMS Value, Average Value, Peak Value, Peak Factor And Form Factor in AC

and, site All About Circuits article on Measurements of AC Magnitude

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When the current sine wave in a circuit reaches its peak value before the voltage wave:
  • Correct Answer
    It is said to have a leading power factor
  • It is said to have a lagging power factor
  • It is said to be in phase
  • None of the above

When the current sine wave in a circuit reaches its peak value before the voltage wave:

(A). It is said to have a leading power factor

When the electron flow (amperes) is at max before the max in amount of charge (electrons) differential (volts), then we have a leading power factor.

Power is the ability of voltage (push) and amperes (electron flow) to do a unit of work. If you apply root-means-square formula to the amperes and volts, you get "apparent power."

If you imagine that horizontal line is the real power, and at an angle from that line is another line, called apparent power, then the difference between apparent power and real power is the reactive power. (such a fun fact)

If the apparent power line is below the horizontal real power line, then we have the leading power factor If the apparent power line is at an angle above the horizontal real power line, then we have lagging power factor.

"Capacitive loads are leading (current leads voltage), and inductive loads are lagging (current lags voltage)."*

*For more insights, please see Wikipedia's article on Power Factor

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An "harmonic" is:
  • Correct Answer
    A whole multiple of an original frequency
  • The heating value of an RF current
  • The internal impedance of a power source
  • A multiple of the power factor

An "harmonic" is:

(A). A whole multiple of an original frequency

Harmonic is the same note, but some octaves higher. The wave from zero to max back to zero is divided by a number such as 1,2, or 3 or more.

When you divide the wave it occurs at a higher Hz, at a multiple of the initial Hz wave. So, if the initial wave is at 440 Hz, then the second harmonic will be at 880 Hz, and there will be two waves in the time unit of the initial one.

The 3rd harmonic will have three smaller waves in the time unit of the initial wave, and the initial frequency in Hz will be multiplied by 3.

Harmonics are important in music and radio waves. In radio waves, there are circuits to eliminate the harmonics of the frequency desired, to suppress interference.

For more info, please see Wikipedia's article on Harmonic

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Assuming a power source to have a fixed value of internal impedance, maximum power will be transferred to the load when:
  • Correct Answer
    The load impedance equals the internal impedance of the source
  • The load impedance is higher than the source impedance
  • The load impedance is lower than the source impedance
  • None of the above

Assuming a power source to have a fixed value of internal impedance, maximum power will be transferred to the load when:

(A.) The load impedance equals the internal impedance of the source


Impedance is the resistance to alternating current. Impedance is created by the resistance (opposition to flow of electrons, in ohms) and reactance. Reactance includes inductive and capacitive components.
See Wikipedia's article on Electrical Impedance


Impedance matching seeks to maximize the amount of power transferred while minimizing the reflection from the load transferred.

Basically, if the impedance of the input load is the same as the internal impedance of the output (the source), then the maximum amount of power is transferred.
For more info, see Wikipedia's article on Impedance matching

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When two sine waves of the same frequency do not reach their maximum or minimum values simultaneously:
  • A phase difference exists
  • A phase difference does not exist
  • The sign waves are out of phase
  • Correct Answer
    A & C

When two sine waves of the same frequency do NOT reach their maximum or minimum values simultaneously:

(D). A & C

  • A phase difference exists
  • The sign waves are out of phase

Alternating current creates a sine wave as electric motor rotates between north and south magnetic poles in a coil. See Electronic Tutorials Sinusoidal Waveforms article.


When voltage sine wave leads current (ELI) inductance is the result. When current sine wave leads voltage (ICE), then result is capacitance.
(ELI the ICE man)
E voltage, L inductor, I current;
I current, C capacitor, E voltage


Please see Wikipedia's animated illustration on the relationship of Phases and Sine waves. You can see that when there is no phase difference, the combined sine wave is at maximum.

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Which method may be used to obtain more than one value of voltage from a fixed DC source?
  • Use a resistance type voltage divider
  • Connect voltage regulator tubes of suitable values and tap off the desired output voltage
  • Correct Answer
    Both A & B
  • None of the above

Which method may be used to obtain more than one value of voltage from a fixed DC source?

(C). Both A & B

  • Use a resistance type voltage divider

  • Connect voltage regulator tubes of suitable values and tap off the desired output voltage

For insights regarding DC current, please see IQS Directory site's article on DC Power Supply

For well illustrated practical application of variable DC current, please see How To Get Variable Voltage From a Fixed DC Power Supply

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The conductance (G) of a circuit if 6 A flows when 12 VDC is applied is:
  • Correct Answer
    0.5 mho
  • 1.0 mho
  • 0.25 mho
  • None of the above

The conductance (G) of a circuit if
6 A flows when
12 VDC is applied is:

(A). 0.5 mho

mho is the 1/ohms yielding conductance.

Conductance (G), is 1/R or I/V.

G = 6 A / 12 VDC = 0.5 mho

For more info, please see Wikipedia's article on Electrical resistance and conductance

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Two 10 W, 500 ohm resistors in parallel will dissipate how many watts?
  • Correct Answer
    20 watts
  • 10 watts
  • 30 watts
  • 40 watts

Two (2) 10 W,
500 ohm resistors
in parallel will dissipate how many watts?

(A). 20 watts

Formulas for power dissipation:

Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms

Because both resistors in parallel are the same value:
2 quantity (each 500 ohms) x 10 Watts = 20 Watts

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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A 20 ohm resistor with a current of 0.25 A passing through it will dissipate how many watts?
  • 10 watts
  • 20 watts
  • 0.025 watts
  • Correct Answer
    1.25 watts

A 20 ohm resistor with a current of
0.25 A passing through it
will dissipate how many watts?

(D). 1.25 watts

Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms

Watts = 0.25 A (2) x 20 ohms
Watts = 0.0625 A x 20 ohms
Watts = 1.25

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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If the voltage to a circuit is doubled and the resistance is increased to three times the original value, what will be the final current?
  • 1/3 the original current
  • Correct Answer
    2/3 the original current
  • 3 times the original current
  • None of the above

If the voltage to a circuit is doubled
and the resistance is increased to three times the original value,
what will be the final current?

(B). 2/3 the original current

Voltage x 2 and Resistance * 3 ==> Amperes?

Voltage = Amperes x Ohms
Amperes = Voltage / Ohms
Amperes = 2V/3R which is 2/3 original amperes

For more info, please see Electrical 101 site article on Ohm’s Law

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If a vacuum tube with a filament rating of 0.25 A and 5 V is operated from a 6 volt battery, what value of resistor is necessary?
  • Correct Answer
    4 ohms
  • 5 ohms
  • 10 ohms
  • 2 ohms

If a vacuum tube with a filament rating of
0.25 A and
5 V is operated from a
6 volt battery,
what value of resistor is necessary?

(A). 4 ohms

Ohms = Volts / Amperes
Ohms = 6 volts / 0.25 Amperes = 24
Ohms = 5 volts / 0.25 Amperes = 20
24 ohms - 20 ohms = 4 ohms

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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The minimum power dissipation rating of a resistor of 20,000 ohms across a potential of 500 V should be:
  • Correct Answer
    25 watts
  • 12.5 watts
  • 15 watts
  • None of the above

The minimum power dissipation rating of a resistor of
20,000 ohms across a potential of
500 V should be:

(A). 25 watts

Watts = Volts(2) / ohms
Watts = 500 ohms (2) / 20,000 = 12.5 watts
12.5 watts x 2 = 25 watts

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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The total power dissipation capability of two 10 watt, 500 ohm resistors connected in series is:
  • Correct Answer
    20 watts
  • 10 watts
  • 5 watts
  • None of the above

The total power dissipation capability of
two 10 watt,
500 ohm resistors
connected in series is:

(A). 20 watts

Formulas for power dissipation:

Watts = Volts x Amperes or Watts = Volts(2) / Ohms or Watts = Amperes(2) x Ohms

Because both resistors in parallel are the same value: 2 quantity (each 500 ohms) x 10 Watts = 20 Watts

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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What is the total power dissipation capability of two 10 watt 500 ohm resistors connected in parallel?
  • Correct Answer
    20 watts
  • 40 watts
  • 5 watts
  • None of the above

What is the total power dissipation capability of
two 10 watt
500 ohm resistors
connected in parallel?

(A). 20 watts

Formulas for power dissipation:

Watts = Volts x Amperes or Watts = Volts(2) / Ohms or Watts = Amperes(2) x Ohms

Because both resistors in parallel are the same value: 2 quantity (each 500 ohms) x 10 Watts = 20 Watts

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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What is the maximum current carrying capacity of a resistor of 5000 ohms, 200 watts?
  • Correct Answer
    0.2 A
  • 1 A
  • 1.2 A
  • None of the above

What is the maximum current carrying capacity of a resistor of
5000 ohms,
200 watts?

(A). 0.2 A

Watts = Volts x Amperes or
Watts = Volts(2) / Ohms or
Watts = Amperes(2) x Ohms

200 watts = 5000 ohms x X(2) Amperes

X(2) = 200 / 5000 = Square Root of 0.04 = 0.2 A

For more info, please see All About Circuits site, article Power Calculations Chapter 5 - Series And Parallel Circuits

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What is the total resistance of a parallel circuit consisting of a 10 ohm branch and a 25 ohm branch?
  • @ ohms
  • 10.3 ohms
  • 7.0 ohms
  • Correct Answer
    7.14 ohms

What is the total resistance of
a parallel circuit consisting of a
10 ohm branch and a
25 ohm branch?

(D). 7.14 ohms

To sum up parallel resistors, you need to take the reciprocal of the resistors.

1/10 + 1/25 = 0.1 + 0.04 = 0.14,
so reciprocal of 1/0.14 =7.14

For more info, please see All About Circuits site, article Parallel Resistance Calculator

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The current through two resistors in series is 3 A. Resistance #1 is 50 ohms, resistance #2 drops 50 V across its terminals. What is the total voltage?
  • Correct Answer
    200 V
  • 220 V
  • 110 V
  • 180 V

The current through two (2) resistors in series is
3 A. Resistance
#1 is 50 ohms, resistance
#2 drops 50 V across its terminals.
What is the total voltage?

(A). 200 V

Voltage = Amperes x Resistance

3 Amperes x 50 Ohms = 150 Volts
since 50 Volts drop is given,
then 150 V + 50 V = 200 V

For more information, please see Sciencing site article on How to Calculate a Voltage Drop Across Resistors

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An 18 ohm and a 15 ohm resistor are connected in parallel; a 36 ohm resistor is connected in series with this combination; a 22 ohm resistor is connected in parallel with this total combination. The total current is 5 A. What current is flowing in the 15 ohm resistor?
  • Correct Answer
    0.908 A
  • 1.000 A
  • 1.908 A
  • 0.809 A

An 18 ohm and a 15 ohm resistor are connected in parallel;
a 36 ohm resistor is connected in series with this combination;
a 22 ohm resistor is connected in parallel with this total combination.
The total current is 5 A.
What current is flowing in the 15 ohm resistor?

(A). 0.908 A

Amperes = Volts / Resistance.

  1. Determine combined resistance, in parallel of 18 and 15 ohms. Use 1/x for addition of parallel resistors.
  2. The series circuit adds 36 ohms. Straight addition.
  3. Determine combined resistance, in parallel of 22 ohms . Again, need to use 1/x to add the previous resistance and the 22 ohms here. This is the total resistance.
  4. The total current is 5 Amperes.

(1) In parallel
1/18 + 1/15 = 15/ 270 + 18 / 270 = 33 / 270 = 0.122 or about 8.18

(2) In series
8.18 + 36 = 36.122 = 44.18 ohms

(3) In parallel
44.18 ohms + 22 ohms = 14.686 ohms

(4) To derive Volts
14.686 ohms x 5 Amperes = 73.43 Volts

Then, you have to work back Amperes to the 15 ohm resistor. Calculate branch currents without voltage

Remember, Amperes flow through series unchanged, but divide in parallel, depending on the resistor.

For more info on parallel and series circuits, see BCampus site article 63 Resistors in Series and Parallel

For more information, please see Sciencing site article on How to Calculate a Voltage Drop Across Resistors

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A circuit passes 3 A. The internal resistance of the source is 2 ohms. The total resistance is 50 ohms. What is the terminal voltage of the source?
  • Correct Answer
    150 V
  • 100 V
  • 110 V
  • 240 V

A circuit passes 3 A.
The internal resistance of the source is 2 ohms.
The total resistance is 50 ohms.
What is the terminal voltage of the source?

(A). 150 V

The formula V=IR can be used.
3Ampers x 50 Ohms = 150 Volts

For more info, see Science by Degrees site's article Why V=IR is not Ohm’s Law, and why that matters

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A relay coil has 500 ohms resistance, and operates on 125 mA. What value of resistance should be connected in series with it to operate from 110 VDC?
  • Correct Answer
    380 ohms
  • 400 ohms
  • 200 ohms
  • None of the above

A relay coil has
500 ohms resistance, and operates on
125 mA. (0.125 A)
What value of resistance should be connected in series with it to operate from 110 VDC?

(A). 380 ohms

For resistance in series circuits, you simply add resistance of each component. See Understanding & Calculating Series Circuits Basic Rules from swtc.edu

V=IR
110 V = (500 ohms + X ohms) * .125 A
(500 ohms + X ohms) = 110 v / .125 A
(500 ohms + X ohms) = 880 ohms
X = 880 ohms - 500 ohms = 380 ohms

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Given: Input power to a receiver is 75 watts. How much power does the receiver consume in 24 hours of continuous operation?
  • 1800 watthours
  • 1.80 kilowatthours
  • Correct Answer
    A & B
  • None of the above

Given: Input power to a receiver is 75 watts. How much power does the receiver consume in 24 hours of continuous operation?

(C). A & B

  • 1800 watt hours
  • 1.80 kilowatt hours

Both answers are the same.
Kilo is 1000, so 1800/1000=1.80

75 Watts x 24 hours = 1,800 Watts

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The total reactance when two capacitances of equal value are connected in series is:
  • The product of the two individual reactances in ohms
  • Correct Answer
    The sum of the two individual reactances in ohms
  • The difference of the two individual reactances in ohms
  • None of the above

The total reactance when two capacitances of equal value are connected in series is:

(B). The sum of the two individual reactances in ohms

For insight, please see Lumen Physics site the article on Resistors in Series and Parallel also Capacitors in Series and Parallel

And, from Electronics Tutorials site the article on Capacitors in Series, and Capacitors in Parallel

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A capacitor's charge is stored:
  • Upon the inner surface of the capacitor plates
  • As an electrostatic field which exists in the space between the plates
  • Correct Answer
    A & B
  • None of the above

A capacitor's charge is stored:

(C). A & B

  • Upon the inner surface of the capacitor plates

  • As an electrostatic field which exists in the space between the plates

For details, please see OPENPRESS.USASK.CA site article on 4.3 Energy Stored in a Capacitor

Also, see Lumen Physics site article on Energy Stored in Capacitors

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The voltage drop across an individual capacitor of a group of capacitors connected in series across an AC source is:
  • Inversely proportional to the ratio of the capacitance of the capacitor being considered
  • Inversely proportional to the total capacitance of the combination
  • Directly proportional to the applied voltage across the series combination
  • Correct Answer
    All of the above

The voltage drop across an individual capacitor of a group of capacitors connected in series across an AC source is:

(D). All of the above

  • Inversely proportional to the ratio of the capacitance of the capacitor being considered

  • Inversely proportional to the total capacitance of the combination

  • Directly proportional to the applied voltage across the series combination

For more info, please see Electronics Tutorials site article Capacitors in Series

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What is the total capacitance of the capacitors of 3, 5, and 7 microfarad connected in series?
  • 14.79 microfarad
  • Correct Answer
    1.479 microfarad
  • 15 microfarad
  • None of the above

What is the total capacitance of the capacitors of 3, 5, and 7 microfarad connected in series?

(B). 1.479 microfarad

1/3 is 0.33333333333
1/5 is 0.2
1/7 is 0.14285714285

The total is 0.67619014285 and the reciprocal 1/67619014285 is 1.479

For more info, see Lumen Physics article on Capacitors in Series and Parallel

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If capacitors of 3, 5, and 7 microfarad are connected in parallel, what is the total capacitance?
  • Correct Answer
    9 microfarad
  • 15 microfarad
  • 10 microfarad
  • 3 microfarad

If capacitors of 3, 5, and 7 microfarad are connected in parallel, what is the total capacitance?

(A). 9 microfarad

The formula calls for simple addition, which comes to 15, and not 9. Seems like an error. Best, just remember that answer. Checked in the FCC Element 6 question pool, and it is 9.

For more info, see Lumen Physics article on Capacitors in Series and Parallel

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How many capacitors of 400 volts and 2 microfarad each would be necessary to obtain a combination rated at 1600 volts and 1.5 microfarad?
  • 10
  • Correct Answer
    12
  • 14
  • 16

How many capacitors of
400 volts and
2 microfarad each would be necessary to obtain a combination rated at
1600 volts and
1.5 microfarad?

(B). 12

Please see Physics Forum site for explanation of the answer.

See DigiKey Electronics for Series and Parallel Capacitor Calculator

See Open Press site for 6.3 Kirchhoff’s Rules

For basic info, see Electronics Tutorials site for Capacitance and Charge

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If a turn in an inductor is shorted:
  • There will be an decrease of induction
  • There will be a decrease of Q
  • There will be overheating with possible burnout
  • Correct Answer
    All of the above

If a turn in an inductor is shorted:

(D). All of the above

There will be:

  • decrease of induction
  • a decrease of Q
  • overheating with possible burnout

The question does not specify whether it is a DC or AC circuit. One property of an inductor is that it resists changes in amperes.

However, the inductance to the flow of amperes is not the same in DC and AC circuits, measured in di/dt, or change in amperes per change in a unit of time. In DC circuits, the coil stores energy, in AC circuits, the coil stores and delivers energy.

Because of the change (decrease in induction), the flowining amperes may overheat the circuit.

Coils do have some resistance, Q, and short may cause a decrease in Q, as it causes some energy loss.


For more info on inductors (chokes), please see Electronic Tutorials site for article on The Inductor

and for even more details, please see Voltech website for the article on Methods for Detection of Shorted Windings

Regarding Q in coils, please see Electronics Notes article on Inductor Q, Quality Factor

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The relationship between the number of turns and the inductance of a coil may be expressed by:
  • Correct Answer
    The inductance varies approximately as the square of the number of turns
  • The inductance varies approximately as the square root of the number of turns
  • Both A & B
  • None of the above

The relationship between the number of turns and the inductance of a coil may be expressed by:

(A). The inductance varies approximately as the square of the number of turns


For more info, please see Quora article on Why is inductance (L) proportional with turns-square (N²)?

and Electronics Tutorial article on Inductance of a Coil

For more info on inductors (chokes), please see Electronic Tutorials site for article on The Inductor

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The formula for determining the resonant frequency of a circuit when the inductance and capacitance are known is:
  • f = 1/(2 pi times the square root of LC)
  • f = 0.159/(the square root of LC)
  • Correct Answer
    Both A & B
  • None of the above

The formula for determining the resonant frequency of a circuit when the inductance and capacitance are known is:

(C). Both A & B

  • f = 1/(2 pi times the square root of LC)

  • f = 0.159/(the square root of LC)

When you graph frequency on X axis, and reactance on Y axis, the inductive reactance is a straight 45 degrees line, but the capacitive reactance curve starts high and decreases as frequency increases.

At the intersection of both, there is the resonant frequency for a specific circuit. It is when the inductive and capacitive reactance are equal. For more info, please see Cadence site, article on What is Resonant Frequency?

Also, for more details see Electronics Tutorials article on Series Resonance Circuit

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The formula for determining the wavelength when the frequency is known is:
  • Wavelength = 300,000/ f kHz
  • Wavelength = 300,000,000/ f Hz
  • Wavelength = 300/ f MHz
  • Correct Answer
    All of the above

The formula for determining the wavelength when the frequency is known is:

(D). All of the above

  • Wavelength = 300,000/ f kHz

  • Wavelength = 300,000,000/ f Hz

  • Wavelength = 300/ f MHz

For graphic explanation, see wikiHow article on How to Calculate Wavelength,
and on Study site, How to Calculate Wavelength, which offers a video and info.

For explanation on metric system of units, kilo, and mega, see Wikipedia's article on Metric prefix

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The wavelength of the period of one complete cycle of a radio wave of 0.000,001 second is:
  • Correct Answer
    300 M
  • 3000 M
  • 30 M
  • 70 cm

The wavelength of the period of one complete cycle of a radio wave of 0.000,001 second is:

(A). 300 M

Since waves travel in vacuum at 300,000 km/second, or 3,000,000 meters per second, multiply by 1,000,000 to get the second, or 300 M (M=1,000,000).

For details, see Socratic Q&A site article on How can I calculate the wavelength of electromagnetic radiation?

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The efficiency of a radio device is:
  • The ratio of the power input to the power output
  • Correct Answer
    The ratio of the useful power output to the power input
  • The ratio of the minimum power output to the maximum power output
  • None of the above

The efficiency of a radio device is:

(B). The ratio of the useful power output to the power input

Generally, efficiency of any system is the cost or amount of what is provided, and the benefits achieved.

For radio, it is the amount of energy as input, and the amount of energy as output, with the difference being radiated during the processing.

For more info, see Socratic Q&A site for How can energy efficiency be calculated?

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What is the total impedance of a parallel capacitor and inductor with equal values of reactance?
  • Infinite total reactance
  • Zero total reactance
  • Parallel impedance is resistive and infinite
  • Correct Answer
    B & C

What is the total impedance of a parallel capacitor and inductor with equal values of reactance?

(D). B & C

  • Zero total reactance
  • Parallel impedance is resistive and infinite

For explanation of impedance and reactance please see Electronics Tutorial site for article on Impedance and Complex Impedance

Also, see EE Power site for article on Impedance and Reactance

Specific explanation here on Electrical Engineering article on Infinite impedance at resonance in parallel LC circuit ? does that mean it is not usable?

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The total inductance of two coils in parallel without any mutual coupling is:
  • Correct Answer
    Equal to the product of the two inductances divided by their sum
  • The sum of the individual inductances
  • Zero
  • None of the above

The total inductance of two coils in parallel without any mutual coupling is:

(A). Equal to the product of the two inductances divided by their sum

If coupling in the circuit of two coils present, then the total amount of inductance will be affected by the total amount of coupling.

For explanation of the formula, please see Electronics Tutorial site, for the article on
Inductors in Parallel,
paragraph on the "Parallel Inductor Equation."

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What is the total reactance of a series AC circuit, with no resistance and equal inductance and capacitive reactances?
  • The two reactances cancel being equal and opposite
  • Net impedance is purely resistive and contains no reactive component
  • The total reactance is zero at the resonant frequency
  • Correct Answer
    All of the above

What is the total reactance of a series AC circuit, with no resistance and equal inductance and capacitive reactances?

(D). All of the above

  • The two reactances cancel being equal and opposite
  • Net impedance is purely resistive and contains no reactive component
  • The total reactance is zero at the resonant frequency

For full explanation, please see Electronics Tutorials article on AC Inductance and Inductive Reactance

Also, a great article on Reactance, Inductive and Capacitive listed on the Lumen Learning site.

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The total inductance of two coils in series without any mutual coupling is:
  • Correct Answer
    The sum of the individual inductances
  • The product of the individual inductances divided by their sum
  • Infinite
  • None of the above

The total inductance of two coils in series without any mutual coupling is:

(A). The sum of the individual inductances

If coupling in the circuit of two coils present, then the total amount of inductance will be affected by the total amount of coupling.

For explanation of the formula, please see Electronics Tutorial site, for the article on
Inductors in Parallel,
paragraph on the "Parallel Inductor Equation."

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One wave-length is:
  • The distance a wave will travel in the time for one cycle
  • Centimeter wavelength = 30,000 / frequency MHz
  • Correct Answer
    A and B
  • Neither A or B

One wave-length is:

(C). A and B

  • The distance a wave will travel in the time for one cycle

  • Centimeter wavelength = 30,000 / frequency MHz

Need to watch out for the units of measure here. We know that light travels at the speed of 300,000,000 meters per second.

The standard formula for wavelength is 300,000,000 meters/second or 300M divided by radio frequency in Hz.

The time unit for the wave is a second. Thus, we state that so many waves occurred in one second.

So, if we use MHz instead of Hz, then we have to adjust the units of speed of light in the formula.

We know that 1 MHz equals to 1,000,000 Hz. And, we know that there are 100 centimeters in a meter.

Then, if we multiply the 300,000,000 meters/second by 100 centimeters/one meter, we get 30,000,000,000 centimeters/second.

To convert Hz to MHz, we must divide by 1,000,000 Hz in 1 MHz, to get 30,000 centimeters per MHz.

Please see NewHams.Info site article on Wavelength. This site is a good resource for various radio topics.

To calculate wavelengths, and try out various units, please see Wavelength Calculator site for Wavelength Calculator

BTW: A great listing of FCC radio frequency allocations is an FCC Online Table Frequency Allocations. Good to print out and keep as reference for when choosing frequencies.

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In an AC circuit, a series inductance acting alone:
  • Correct Answer
    Causes the current to lag the applied voltage by 90 degrees
  • Causes the current to lead the applied voltage by 90 degrees
  • Causes the current to lag the applied voltage by 45 degrees
  • Causes the current to lead the applied voltage by 45 degrees

In an AC circuit, a series inductance acting alone:

(A). Causes the current to lag the applied voltage by 90 degrees

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Shock excitation into an L-C circuit is the result of:
  • A voltage being momentarily introduced
  • The capacitor may be charged
  • The inductor may have a voltage induced
  • Correct Answer
    All of the above

Shock excitation into an L-C circuit is the result of:

(D). All of the above

  • A voltage being momentarily introduced
  • The capacitor may be charged
  • The inductor may have a voltage induced

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The term cathode ray usually applies to:
  • Correct Answer
    A fairly high velocity electron beam
  • Background noise
  • The logarithm gain of an electron beam
  • None of the above

The term cathode ray usually applies to:

(A). A fairly high velocity electron beam

There are two guns that shoot electron beam at a storage mash. The main beam shoots "fairly high velocity electron beam," to create the picture. The other gun illuminates the mesh by shooting the low velocity electron beam. It does not interfere with the main beam.

For more info, please see Wikipedia's article on Cathode-ray tube

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Shielding an RF inductance:
  • Increases the losses of the inductance
  • Lowers the inductance value and the Q
  • Increases the coil capacity to the shield
  • Correct Answer
    All of the above

Shielding an RF inductance:

(D). All of the above

  • Increases the losses of the inductance
  • Lowers the inductance value and the Q
  • Increases the coil capacity to the shield

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The tendency of a tank circuit to keep oscillating for a time after the excitation energy has been removed is:
  • Push-pull effect
  • Correct Answer
    Flywheel effect
  • Polarizing effect
  • Parasitic oscillation

The tendency of a tank circuit to keep oscillating for a time after the excitation energy has been removed is:

(B). Flywheel effect

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Power factor is defined as:
  • The ratio between the resistance and the impedance in a circuit
  • The ratio between the true power and the apparent power of a circuit
  • Correct Answer
    Both A&B
  • None of the above

Power factor is defined as:

(C). Both A&B

  • The ratio between the resistance and the impedance in a circuit

  • The ratio between the true power and the apparent power of a circuit

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High or low frequency oscillations occurring in circuits other than the original tank desired output frequencies are:
  • Harmonics
  • Correct Answer
    Parasitic oscillations
  • Hysteresis
  • Eddy currents

High or low frequency oscillations occurring in circuits other than the original tank desired output frequencies are:

(B). Parasitic oscillations

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What are effects of parasitic oscillations?
  • Change of bias
  • Reduced efficiency of the amplifier tube
  • Distortion of the modulated wave
  • Correct Answer
    All of the above

What are effects of parasitic oscillations?

(D). All of the above

  • Change of bias
  • Reduced efficiency of the amplifier tube
  • Distortion of the modulated wave

If you ever heard a microphone whine in the amplifier, you heard parasitic oscillation, which is what you don't want in a feedback, or variation in current or voltage.

Whether analog or digital processing, the undesirable feedback can occur. It occurs when part of the output is processed as input.

For more info, please see Wikipedia's article on Parasitic oscillation

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The velocity of propagation of radio frequency waves in free space is:
  • 300,000 meters / second
  • 186,284 miles / second
  • The same as the velocity of light in free space
  • Correct Answer
    All of the above

The velocity of propagation of radio frequency waves in free space is:

(D). All of the above

  • 300,000 meters / second or 3 x 10 (8) m/s
  • 186,284 miles / second
  • The same as the velocity of light in free space

The Speed of Radio Wave == frequency times wavelength.
Thus, since the speed is 300 km per second divided by Frequency in MHz will yield the wavelength.

See EverythingRF site for Wavelength to Frequency Calculator

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To double the resonant frequency of a resonant circuit:
  • Make C one third of its original value
  • Correct Answer
    Make L and C both half their original values
  • Decreasing the value of both L and C in any proportion so that their product will be one-half of the original values
  • None of the above

To double the resonant frequency of a resonant circuit:

(B). Make L and C both half their original values

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How may the Q of a parallel resonant circuit be increased?
  • Increasing coupling to the resonant circuit
  • Using coil and capacitor supports of special low - loss materials
  • Correct Answer
    Both A and B
  • Decreasing coupling to the resonant circuit

How may the Q of a parallel resonant circuit be increased?

(C). Both A and B

  • Increasing coupling to the resonant circuit
  • Using coil and capacitor supports of special low - loss materials

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If L and C in a parallel resonant circuit resonants at 1000 kHz are so varied that their product remains constant, what will be the resulting resonant frequency?
  • 10,000 kHz
  • 100 kHz
  • Correct Answer
    1 MHz
  • None of the above

If L and C in a parallel resonant circuit resonants at 1000 kHz are so varied that their product remains constant, what will be the resulting resonant frequency?

(C). 1 MHz

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What is the resonant frequency of a tuned circuit consisting of a 500 picofarad capacitor, a 150 microfarad tuning coil, and 10 ohms resistance?
  • Correct Answer
    581 kHz
  • 753 kHz
  • 498 kHz
  • None of the above

What is the resonant frequency of a tuned circuit consisting of a 500 picofarad capacitor, a 150 microfarad tuning coil, and 10 ohms resistance?

(A). 581 kHz

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What is voltage regulation as applied to power supplies?
  • Correct Answer
    The ratio of change in voltage between no load and full load to the full-load voltage output
  • The ratio of output to input voltage
  • Voltage output of the power supply under full load
  • The ratio of input to output voltage

What is voltage regulation as applied to power supplies?

(A). The ratio of change in voltage between no load and full load to the full-load voltage output

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An EMF may be generated by sound waves by what principle?
  • Electrostatic
  • Piezo-electric
  • Resistance change
  • Correct Answer
    All of the above

An EMF may be generated by sound waves by what principle?

(D). All of the above

  • Electrostatic
  • Piezo-electric
  • Resistance change

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How can you correct power factor in an electrical circuit?
  • Inductance is used to correct a leading angle
  • Capacitance is used to correct a lagging angle
  • Neither A or B
  • Correct Answer
    Both A and B

How can you correct power factor in an electrical circuit?

(D). Both A and B

  • Inductance is used to correct a leading angle
  • Capacitance is used to correct a lagging angle

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Permeability is:
  • The magnetic field created by a conductor wound on a laminated core and carrying any electric current
  • Correct Answer
    The ratio of magnetic flux density in a substance to the magnetizing force which produces it
  • Polarized molecular alignment in a ferromagnetic material while under the influence of a magnetizing force
  • Both A and C

Permeability is:

(B). The ratio of magnetic flux density in a substance to the magnetizing force which produces it

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The time in seconds for a capacitor to attain 63.2 % of the applied voltage across its terminals is:
  • Twice the natural period of oscillation of the circuit
  • Varactance
  • Correct Answer
    Time constant
  • Equal to the ohmic resistance of the circuit

The time in seconds for a capacitor to attain 63.2 % of the applied voltage across its terminals is:

(C). Time constant

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What is the reactance of a 2-henry choke at 3000 Hz?
  • 5300 ohms
  • Correct Answer
    37,680 ohms
  • 376,800 ohms
  • 53,000 ohms

What is the reactance of a 2-henry choke at 3000 Hz?

(B). 37,680 ohms

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If there is no resistance in either leg of a circuit with an inductance of 5 henrys in parallel with a capacitance of 1 microfarad, what is the equivalent impedance of the parallel network circuit?
  • Zero
  • Correct Answer
    Infinite
  • Median
  • None of the above

If there is no resistance in either leg of a circuit with an inductance of 5 henrys in parallel with a capacitance of 1 microfarad, what is the equivalent impedance of the parallel network circuit?

B. Infinite

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What is the total impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?
  • 15 ohms
  • 27 ohms
  • Correct Answer
    18 ohms
  • 5 ohms

What is the total impedance of a series AC circuit having a resistance of 6 ohms, an inductive reactance of 17 ohms, and zero capacitive reactance?

(C). 18 ohms

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The total impedance of a series AC circuit with an inductive reactance of 24 ohms, a resistance of 16 ohms, and a capacitive reactance of 16 ohms is:
  • 20 ohms
  • Correct Answer
    16 ohms
  • 10 ohms
  • None of the above

The total impedance of a series AC circuit with an inductive reactance of 24 ohms, a resistance of 16 ohms, and a capacitive reactance of 16 ohms is:

(B). 16 ohms

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Essentials for making a good solder connection are:
  • Bright, clean parts
  • Plenty of heat with the minimum amount of solder used
  • Discontinue operating on high power
  • Correct Answer
    None of the above

Essentials for making a good solder connection are:

(D). None of the above

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For protection of personnel handling a transmitter:
  • Correct Answer
    Ground all exposed metal parts
  • Transmitter is equipped to shunt grounded faults
  • Discontinue operating on high power
  • None of the above

For protection of personnel handling a transmitter:

A. Ground all exposed metal parts

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The ratio of peak-to-effective voltage values of a sign wave are:
  • 1.414 to 1
  • 1 to 0.707
  • Correct Answer
    Both A and B
  • Neither A or B

The ratio of peak-to-effective voltage values of a sign wave are:

(C). Both A and B

  • 1.414 to 1
  • 1 to 0.707

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The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:
  • Correct Answer
    Reluctance
  • Hysteresis
  • Permeability
  • Eddy currents

The opposition to the creation of magnetic lines of force in a magnetic circuit is known as:

(A). Reluctance

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The ratio of magnetic flux density to the field strength is known as:
  • Residual magnetism
  • Correct Answer
    Permeability
  • Reluctance
  • None of the above

The ratio of magnetic flux density to the field strength is known as:

(B). Permeability

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The magnetic force which remains in a substance after the original magnetizing force has been removed is known as:
  • Reluctance
  • Correct Answer
    Residual magnetism
  • Permeability
  • Hysteresis

The magnetic force which remains in a substance after the original magnetizing force has been removed is known as:

(B). Residual magnetism

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The direction of electron flow through a coil and the manner of winding the turns:
  • Correct Answer
    Influence the direction of magnetic line of force generated by an electromagnet
  • Are determined by the left-hand status rule
  • Are determined by the diameter of the wire and length
  • Both A and C

The direction of electron flow through a coil and the manner of winding the turns:

(A). Influence the direction of magnetic line of force generated by an electromagnet

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Adding an iron core to an air-core inductance:
  • Correct Answer
    Increases the inductance
  • Decreases the inductance
  • Does not affect the inductance
  • Causes parasitic oscillations in the inductor

Adding an iron core to an air-core inductance:

(A). Increases the inductance

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Electromagnets are used in:
  • loudspeakers
  • meters
  • motors
  • Correct Answer
    All of the above

Electromagnets are used in:

(D). All of the above

  • loudspeakers
  • meters
  • motors

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What will be the effect of a small increase in the number of turns upon the field strength of a single layer solenoid?
  • Decrease in field strength if the coil length is increased
  • Unchanged if the spacing is reduced to keep the length constant
  • Correct Answer
    Both A and B
  • None of the above

What will be the effect of a small increase in the number of turns upon the field strength of a single layer solenoid?

(C). Both A and B

  • Decrease in field strength if the coil length is increased

  • Unchanged if the spacing is reduced to keep the length constant

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Can a transformer be used with direct current?
  • In general, no
  • If the DC current is periodically interrupted it would be possible to use an original DC voltage source
  • Correct Answer
    Both A and B
  • None of the above

Can a transformer be used with direct current?

(C). Both A and B

  • In general, no
  • If the DC current is periodically interrupted it would be possible to use an original DC voltage source

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A tube containing either a filament or cathode structure, grid, and a plate is a:
  • Correct Answer
    Triode
  • Tetrode
  • Pentode
  • Diode

A tube containing either a filament or cathode structure, grid, and a plate is a:

(A). Triode

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A tube similar to a triode with the addition of a spirally wound screen grid between the plate and control grid is a:
  • Diode
  • Correct Answer
    Tetrode
  • Pentode
  • Triode

A tube similar to a triode with the addition of a spirally wound screen grid between the plate and control grid is a:

(B). Tetrode

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Theoretical gain of a tube. The ratio of a small change in plate voltage to give a certain small change in plate current to a change in grid which would cause the same current:
  • Correct Answer
    Amplification factor
  • Power factor
  • Maximum inverse plate voltage
  • None of the above

Theoretical gain of a tube. The ratio of a small change in plate voltage to give a certain small change in plate current to a change in grid which would cause the same current:

(A). Amplification factor

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Effectiveness of the grid in causing changes of plate current:
  • Transconductance
  • Mutual conductance
  • Plate resistance
  • Correct Answer
    A & B

Effectiveness of the grid in causing changes of plate current:

(D). A & B

  • Transconductance
  • Mutual conductance

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The maximum negative anode voltage with respect to the cathode. It equals the DC voltage at the input to the plus the peak AC voltage applied during the nonconducting portion of the cycle of operation of the tube:
  • Correct Answer
    Maximum inverse plate voltage
  • Mutual conductance
  • Both A & B
  • None of the above

The maximum negative anode voltage with respect to the cathode. It equals the DC voltage at the input to the plus the peak AC voltage applied during the nonconducting portion of the cycle of operation of the tube:

(A). Maximum inverse plate voltage

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What is the primary purpose of the control grid of the triode?
  • Correct Answer
    To provide a means of obtaining amplification
  • To neutralize RF amplifiers
  • Blocks passage of electrons
  • None of the above

What is the primary purpose of the control grid of the triode?

(A). To provide a means of obtaining amplification

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What is the primary purpose of the screen grid of the tetrode?
  • Reduces the grid to plate capacitance, making it unnecessary to neutralize RF amplifiers except at very high frequencies
  • Makes the plate current substantially independent of plate voltage, permitting much higher values of amplification
  • Correct Answer
    Both A & B
  • None of the above

What is the primary purpose of the screen grid of the tetrode?

(C). Both A & B

  • Reduces the grid to plate capacitance, making it unnecessary to neutralize RF amplifiers except at very high frequencies

  • Makes the plate current substantially independent of plate voltage, permitting much higher values of amplification

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What is the primary purpose of the suppressor grid of a pentode?
  • Correct Answer
    Is highly negative with respect to the plate and returns secondary emission to the plate, increasing the permissible gain and the tube efficiency
  • Reduces interelectrode capacitance between control grid and plate making plate efficiency about 10% greater than a triode
  • Both A & B
  • Neither of the above

What is the primary purpose of the suppressor grid of a pentode?

(A). Is highly negative with respect to the plate and returns secondary emission to the plate, increasing the permissible gain and the tube efficiency

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Thoriated tungsten is usually used to make:
  • Correct Answer
    Filaments
  • Heaters
  • Cathodes
  • None of the above

Thoriated tungsten is usually used to make:

(A). Filaments

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In what types of circuits do beam power vacuum tubes find application?
  • As audio amplifier in the output and power stages of circuits having low to moderately high output ratings
  • As an RF power amplifier
  • Correct Answer
    Both A & B
  • None of the above

In what types of circuits do beam power vacuum tubes find application?

(C). Both A & B

  • As audio amplifier in the output and power stages of circuits having low to moderately high output ratings

  • As an RF power amplifier

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When free electrons in a conductor acquire sufficient energy to leave the conductor and pass into the surrounding space, it is expressed as:
  • Secondary emission
  • Correct Answer
    Electron emission
  • Primary electron release
  • None of the above

When free electrons in a conductor acquire sufficient energy to leave the conductor and pass into the surrounding space, it is expressed as:

(B). Electron emission

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The emission of electrons from a material due to the impact of high-velocity electrons on its surface is:
  • Primary electron emission
  • Correct Answer
    Secondary emission
  • Mimetic emission
  • None of the above

The emission of electrons from a material due to the impact of high-velocity electrons on its surface is:

(B). Secondary emission

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Characteristics of a vacuum tube operating as a class A amplifier:
  • Correct Answer
    Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape
  • Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output
  • High efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape
  • None of the above

Characteristics of a vacuum tube operating as a class A amplifier:

(A). Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape

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Characteristics of a vacuum tube operating as a class B amplifier:
  • Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape
  • Correct Answer
    Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output
  • High efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape
  • None of the above

Characteristics of a vacuum tube operating as a class B amplifier:

(B). Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle, medium power output

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Factors which determine bios voltage of a vacuum tube:
  • Class of operation, plate supply voltage, permissible distortion
  • Grid signal magnitude, permissible plate dissipation, desired amplification factor
  • The no-signal plate current desired, the desirability of drawing grid current
  • Correct Answer
    All of the above

Factors which determine bios voltage of a vacuum tube:

(D). All of the above

  • Class of operation, plate supply voltage, permissible distortion

  • Grid signal magnitude, permissible plate dissipation, desired amplification factor

  • The no-signal plate current desired, the desirability of drawing grid current

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In the usual Class A amplifier:
  • Correct Answer
    There is no grid current
  • Plate current flows slightly more than 180 degrees of each cycle
  • Biased to twice
  • None of the above

In the usual Class A amplifier:

(A). There is no grid current

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The DC bias in a Class A amplifier:
  • Correct Answer
    Usually is negative as measured at the grid with respect to cathode
  • Usually is positive as measured at the grid with respect to cathode
  • Cannot be determined
  • None of the above

The DC bias in a Class A amplifier:

(A). Usually is negative as measured at the grid with respect to cathode

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What is the effect of incorrect grid bias in a Class A amplifier?
  • Distortion of the output waveshape
  • Possible excessive plate dissipation if the bias is too low
  • Correct Answer
    Both A & B
  • None of the above

What is the effect of incorrect grid bias in a Class A amplifier?

(C). Both A & B

  • Distortion of the output waveshape

  • Possible excessive plate dissipation if the bias is too low

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The approximate efficiency of a Class A vacuum tube amplifier:
  • Correct Answer
    20%-30%
  • 60%
  • 85%
  • 100%

The approximate efficiency of a Class A vacuum tube amplifier:

(A). 20%-30%

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The approximate efficiency of a Class B vacuum tube amplifier:
  • 20%-30%
  • Correct Answer
    60%
  • 85%
  • 100%

The approximate efficiency of a Class B vacuum tube amplifier:

(B). 60%

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The approximate efficiency of a Class C vacuum tube amplifier:
  • 20%-30%
  • 60%
  • Correct Answer
    85%
  • 100%

The approximate efficiency of a Class C vacuum tube amplifier:

(C). 85%

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A charge due to the accumulation of negative electrons because the plate potential cannot attract all of the electrons leaving the emitter:
  • Getter
  • Correct Answer
    Space charge
  • Plate saturation
  • None of the above

A charge due to the accumulation of negative electrons because the plate potential cannot attract all of the electrons leaving the emitter:

(B). Space charge

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A material flashed by the application of heat after the tube is evacuated that absorbs any gases remaining inside the tube:
  • Space charge
  • Correct Answer
    Getter
  • Collector
  • Emitter

A material flashed by the application of heat after the tube is evacuated that absorbs any gases remaining inside the tube:

(B). Getter

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What types of vacuum tube filaments are reactivated:
  • Barium berylliate
  • Correct Answer
    Thoriated tungsten
  • Nickel
  • Thorium oxide

What types of vacuum tube filaments are reactivated:

(B). Thoriated tungsten

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A tungsten filament is operated at ____ temperature than a thoriated tungsten filament:
  • Correct Answer
    A higher
  • A lower
  • The same
  • Unknown

A tungsten filament is operated at ____ temperature than a thoriated tungsten filament:

(A). A higher

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The presence of gas within a tube is indicated:
  • Correct Answer
    By a blue glow
  • By a red glow
  • By a yellow glow
  • None of the above

The presence of gas within a tube is indicated:

(A). By a blue glow

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The cathode of an indirectly heated type of vacuum tube should be maintained at nearly the same potential as the heater circuit:
  • To reduce hum pickup into the cathode
  • To prevent breakdown of the insulation between the heater and cathode
  • Correct Answer
    A & B
  • None of the above

The cathode of an indirectly heated type of vacuum tube should be maintained at nearly the same potential as the heater circuit:

(C). A & B

  • To reduce hum pickup into the cathode

  • To prevent breakdown of the insulation between the heater and cathode

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Transmitting tube filaments should be maintained at recommended voltages:
  • To realize the greatest life-expectancy
  • If the filament voltage is too low, the emission will be reduced and operation of the circuit may be adversely affected
  • If the voltage is too high, the filament may burn out
  • Correct Answer
    All of the above

Transmitting tube filaments should be maintained at recommended voltages:

(D). All of the above

  • To realize the greatest life-expectancy

  • If the filament voltage is too low, the emission will be reduced and operation of the circuit may be adversely affected

  • If the voltage is too high, the filament may burn out

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Use of an AC filament supply is desirable:
  • Correct Answer
    Mostly for practical reasons. It is easily obtainable
  • Hum may be introduced into the amplifier
  • A & B
  • None of the above

Use of an AC filament supply is desirable:

(A). Mostly for practical reasons. It is easily obtainable

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If a DC filament supply is used, it is advisable to periodically reverse the polarity of the filament potential:
  • Correct Answer
    To lengthen the life of the filament
  • To lengthen the life of the power source
  • Both A & B
  • None of the above

If a DC filament supply is used, it is advisable to periodically reverse the polarity of the filament potential:

(A). To lengthen the life of the filament

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Bias voltage on the grid of an AF amplifier tube:
  • Determines the operating conditions of the tube
  • The correct value is essential for undistorted Class A output
  • In power amplifiers the plate current must be limited to safe value not to exceed the rated plate dissipation of the tube
  • Correct Answer
    All of the above

Bias voltage on the grid of an AF amplifier tube:

  • Determines the operating conditions of the tube

  • The correct value is essential for undistorted Class A output

  • In power amplifiers the plate current must be limited to safe value not to exceed the rated plate dissipation of the tube

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The screen grid in a vacuum tube:
  • Makes it unnecessary to neutralize RF amplifiers except at very high frequencies,
  • Makes it possible to obtain much higher values of amplification than with triodes
  • Correct Answer
    A & B
  • None of the above

The screen grid in a vacuum tube:

(C). A & B

  • Makes it unnecessary to neutralize RF amplifiers except at very high frequencies,

  • Makes it possible to obtain much higher values of amplification than with triodes

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The suppressor grid in a multielement vacuum tube:
  • Is highly negative with respect to the plate
  • Returns secondary electrons to the plate
  • Increases the permissible gain and the efficiency of the tube
  • Correct Answer
    All of the above

The suppressor grid in a multielement vacuum tube:

(D). All of the above

  • Is highly negative with respect to the plate

  • Returns secondary electrons to the plate

  • Increases the permissible gain and the efficiency of the tube

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The gain of a triode audio amplifier is a function of:
  • Tube transconduction
  • Plate load impedance
  • Transformer step-up (if used)
  • Correct Answer
    All of the above

The gain of a triode audio amplifier is a function of:

(D). All of the above

  • Tube transconduction

  • Plate load impedance

  • Transformer step-up (if used)

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"Load" on a vacuum tube commonly refers to:
  • The impedance through which plate current flows to produce a useful output
  • Increases as the load impedance approaches the internal plate impedance in value
  • Correct Answer
    A & B
  • None of the above

"Load" on a vacuum tube commonly refers to:

(C). A & B

  • The impedance through which plate current flows to produce a useful output

  • Increases as the load impedance approaches the internal plate impedance in value

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A case in which the grid is held at an excessively negative value for a period of time thereby cutting off plate current:
  • Correct Answer
    Blocked grid
  • Blocked plate
  • Motorboating
  • Tuned grid

A case in which the grid is held at an excessively negative value for a period of time thereby cutting off plate current:

(A). Blocked grid

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The maximum power that can be safely and continuously dissipated in heat on the plate:
  • Correct Answer
    Maximum plate dissipation
  • Maximum power dissipation
  • Continuous plate dissipation
  • Plate heat dissipation

The maximum power that can be safely and continuously dissipated in heat on the plate:

(A). Maximum plate dissipation

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Occurs when plate current equals electron emission for any given filament or cathode temperature:
  • Correct Answer
    Plate saturation
  • Electron saturation
  • Filament saturation
  • None of the above

Occurs when plate current equals electron emission for any given filament or cathode temperature:

(A). Plate saturation

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The most desirable factor in the choice of a vacuum tube for a voltage amplifier:
  • A low value of transconductance
  • Correct Answer
    A high value of transconductance
  • High output tube capacitance
  • None of the above

The most desirable factor in the choice of a vacuum tube for a voltage amplifier:

(B). A high value of transconductance

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Lack of requirement for neutralizing, except at ultra high frequencies, is an advantage of a tetrode over ____:
  • Correct Answer
    A Triode
  • A Pentode
  • A & B
  • None of the above

Lack of requirement for neutralizing, except at ultra high frequencies, is an advantage of a tetrode over ____:

(A). A Triode

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Characteristics of a vacuum tube operating as a Class C amplifier:
  • Low plate circuit efficiency, about 25%; practically no grid driving power; plate current flowing for 360 degrees of each cycle; practically no distortion of the output waveshape
  • Plate circuit efficiency, about 50-60%; plate current flows slightly more than 180 degrees of each cycle; medium power output
  • Correct Answer
    High plate circuit efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape
  • None of the above

Characteristics of a vacuum tube operating as a Class C amplifier:

(C). High plate circuit efficiency, up to 80%; plate current drawn in bursts; great distortion of output waveshape

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Plate current flows for less than 180 degrees (about 120 degrees when the grid bias is about twice cutoff value) in what class amplifier?
  • A
  • B
  • Correct Answer
    C
  • AB

Plate current flows for less than 180 degrees (about 120 degrees when the grid bias is about twice cutoff value) in what class amplifier?

(C). C.

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Tubes operated as Class C amplifiers are not suited for audio-frequency amplifiers:
  • Correct Answer
    Because of excessive distortion
  • Because of current requirement
  • Because of reduced life expectancy of the filament
  • None of the above

Tubes operated as Class C amplifiers are not suited for audio-frequency amplifiers:

(A). Because of excessive distortion

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Low plate current may be caused by:
  • Low filament emission and voltage
  • Excessive bias value, shorted screen by-pass capacitor
  • Open grid circuit, low screen grid supply voltage
  • Correct Answer
    All of the above

Low plate current may be caused by:

(D). All of the above

  • Low filament emission and voltage
  • Excessive bias value, shorted screen bypass capacitor
  • Open grid circuit, low screen grid supply voltage

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A tuned circuit made up of inductance and capacitance is:
  • Correct Answer
    An oscillator
  • A neutralizer
  • Voltage divider
  • None of the above

A tuned circuit made up of inductance and capacitance is:

(A). An oscillator

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Some radio-frequency amplifiers must be neutralized:
  • To maintain linear operation
  • Correct Answer
    To prevent sustained oscillations from occurring in the amplifier
  • Sustain feedback
  • None of the above

Some radio-frequency amplifiers must be neutralized:

(B). To prevent sustained oscillations from occurring in the amplifier

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Cavity resonators are:
  • A form of resonant tank circuit
  • Consist of a hollow metal cylinder bead on all sides
  • Have a very high Q and selectivity
  • Correct Answer
    All of the above

Cavity resonators are:

(D). All of the above

  • A form of resonant tank circuit
  • Consist of a hollow metal cylinder bead on all sides
  • Have a very high Q and selectivity

For more info, please see Cadence article on What is a Cavity Resonator and How is One Used in PCB Design

Also, Wikipedia's article on Resonators

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The diode detector:
  • Is square law on weak signals
  • Is practically linear on strong signals
  • Is square law on strong signals
  • Correct Answer
    A & B

The diode detector:

(D). A & B

  • Is square law on weak signals

  • Is practically linear on strong signals

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The functioning of a grid-leak detector:
  • Depends on the ability of the grid leak and capacitor to follow the average grid current variations which are directly proportioned to the modulation envelope
  • Depends on second harmonic distortion
  • Very sensitive to weak signals
  • Correct Answer
    A & C

The functioning of a grid-leak detector:

(D). A & C

  • Depends on the ability of the grid leak and capacitor to follow the average grid current variations which are directly proportioned to the modulation envelope

  • Very sensitive to weak signals

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Characteristic of a square law type of vacuum tube detector:
  • High sensitivity is provided due to the audio output signal amplitude being proportioned to the square of the radio frequency voltage
  • High percentage of second harmonic distortion
  • Works on weak signals only
  • Correct Answer
    All of the above

Characteristic of a square law type of vacuum tube detector:

(D). All of the above

  • High sensitivity is provided due to the audio output signal amplitude being proportioned to the square of the radio frequency voltage

  • High percentage of second harmonic distortion

  • Works on weak signals only

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A diode detector ordinarily produces ____ overall distortion of the audio output wave than does a triode detector:
  • Correct Answer
    Lower
  • Higher
  • Practically the same
  • Either A or B

A diode detector ordinarily produces ____ overall distortion of the audio output wave than does a triode detector:

(A). Lower

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Operating conditions for determining that a tube is being used as a power detector:
  • Bias at about cutoff
  • High input grid resistance
  • Plate circuit rectification
  • Correct Answer
    All of the above

Operating conditions for determining that a tube is being used as a power detector:

(D). All of the above

  • Bias at about cutoff
  • High input grid resistance
  • Plate circuit rectification

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Why is a center top usually provided for vacuum tube plate and grid return circuits when and AC filament supply is used?
  • Correct Answer
    To prevent hum voltage from modulating the normal signals
  • To allow more filament current
  • A & B
  • None of the above

Why is a center top usually provided for vacuum tube plate and grid return circuits when and AC filament supply is used?

(A). To prevent hum voltage from modulating the normal signals

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How would you determine the cathode-bias resistance necessary to provide correct grid bias for an amplifier?
  • Bias equals the IR drop across the cathode
  • Bias is found by dividing the desired DC bias voltage by the total no-signal cathode current
  • For a tetrode or pentode, the screen current must be added to the plate current
  • Correct Answer
    All of the above

How would you determine the cathode-bias resistance necessary to provide correct grid bias for an amplifier?

(D). All of the above

  • Bias equals the IR drop across the cathode

  • Bias is found by dividing the desired DC bias voltage by the total no-signal cathode current

  • For a tetrode or pentode, the screen current must be added to the plate current

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Given the following vacuum tube constants: Gp = 1000 V, Ip = 150 mA, Ig = 10 mA, Grid leaks = 5000 ohms. What would be the grid bias voltage?
  • Correct Answer
    50 V
  • 100 V
  • 25 V
  • None of the above

Given the following vacuum tube constants:
Gp = 1000 V,
Ip = 150 mA,
Ig = 10 mA,
Grid leaks = 5000 ohms.
What would be the grid bias voltage?

(A). 50 V

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What currents will be indicated by a milliammeter connected between the center top of the filament transformer of a tetrode and negative high voltage?
  • Plate current
  • Screen grid current
  • Correct Answer
    Combined plate and screen grid currents
  • None of the above

What currents will be indicated by a milliammeter connected between the center top of the filament transformer of a tetrode and negative high voltage?

(C). Combined plate and screen grid currents

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A dynatron oscillator is a ____ which depends upon the negative resistance characteristic of a tetrode tube for its operation:
  • Correct Answer
    Tuned circuit operation
  • Diode detector
  • Magnetron oscillator
  • Meystron oscillator

A dynatron oscillator is a ____ which depends upon the negative resistance characteristic of a tetrode tube for its operation:

(A). Tuned circuit operation

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Materials which can be used as crystal detectors:
  • Silicon, galena
  • Carborundum, iron pyrites
  • Silicon, iron pyrites
  • Correct Answer
    All of the above

Materials which can be used as crystal detectors:

(D). All of the above

  • Silicon, galena
  • Carborundum, iron pyrites
  • Silicon, iron pyrites

For more info, please see Electronics Notes site, article on Crystal Detector

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A power detector may be operated:
  • As a square law detector
  • As a linear detector
  • Correct Answer
    As either a square law detector or a linear detector
  • None of the above

A power detector may be operated:

(C). As either a square law detector or a linear detector

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Used to multiply the fundamental frequency by two:
  • Correct Answer
    Frequency doubler
  • Harmonic generator with a suitable resonant circuit
  • A & B
  • None of the above

Used to multiply the fundamental frequency by two:

(A). Frequency doubler

For more info, please see Mini-Circuits site article on Frequency Doublers: Introduction, definition of terms, Q&As

Also, please see Wikipedia's article on Frequency multiplier

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When used as an RF amplifier, a pentode vacuum tube:
  • Usually does not require neutralization
  • Usually requires neutralization
  • May require neutralization at ultra-high frequencies
  • Correct Answer
    A & C

When used as an RF amplifier, a pentode vacuum tube:

(D). A & C

  • Usually does not require neutralization

  • May require neutralization at ultra-high frequencies

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A quartz crystal in a radio transmitter:
  • Is used to provide a high degree of master-oscillator frequency stability
  • May be the sole tuned circuit in the oscillator
  • Correct Answer
    A & B
  • None of the above

A quartz crystal in a radio transmitter:

(C). A & B

  • Is used to provide a high degree of master-oscillator frequency stability

  • May be the sole tuned circuit in the oscillator

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Advantage of crystal control over tuned circuit oscillators:
  • Very high Q
  • Compact size
  • Excellent frequency stability
  • Correct Answer
    All of the above

Advantage of crystal control over tuned circuit oscillators:

(D). All of the above

  • Very high Q
  • Compact size
  • Excellent frequency stability

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If the crystal will undergo very small changes in its operating frequency with relatively large temperature variations:
  • A high-temperature coefficient crystal
  • Correct Answer
    A low-temperature coefficient crystal
  • A constant-temperature coefficient crystal
  • None of the above

If the crystal will undergo very small changes in its operating frequency with relatively large temperature variations:

B. A low-temperature coefficient crystal

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A separate source of power is sometimes desirable for crystal-oscillator units in a transmitter:
  • Correct Answer
    To prevent dynamic instability of the crystal oscillator
  • To prevent thermocoupling of the crystal oscillator
  • To prevent overtuning of the crystal oscillator
  • To cause dynamic instability of the crystal oscillator

A separate source of power is sometimes desirable for crystal-oscillator units in a transmitter:

(A). To prevent dynamic instability of the crystal oscillator

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"The temperature coefficient of an x-cut crystal is negative":
  • The operating frequency of the crystal will decrease as the temperature decreases
  • The operating frequency of the crystal will decrease as the temperature increases
  • The operating frequency of the crystal will increase as the temperature decreases
  • Correct Answer
    B & C

"The temperature coefficient of an x-cut crystal is negative":

(D). B & C

  • The operating frequency of the crystal will decrease as the temperature increases

  • The operating frequency of the crystal will increase as the temperature decreases

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If you apply DC voltage to the opposite plane surfaces of a quartz crystal:
  • The crystal plate will always undergo a physical distortion
  • The crystal might crack under the strain of displacement caused by too much voltage
  • Correct Answer
    A & B
  • None of the above

If you apply DC voltage to the opposite plane surfaces of a quartz crystal:

(C). A & B

  • The crystal plate will always undergo a physical distortion

  • The crystal might crack under the strain of displacement caused by too much voltage

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"The temperature coefficient of a y-cut crystal is positive" means:
  • The operating frequency of the crystal will decrease as the temperature decreases
  • The operating frequency of the crystal will increase as the temperature increases
  • The operating frequency of the crystal will decrease as the temperature increases
  • Correct Answer
    A & B

"The temperature coefficient of a y-cut crystal is positive" means:

(D). A & B

  • The operating frequency of the crystal will decrease as the temperature decreases

  • The operating frequency of the crystal will increase as the temperature increases

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Two dissimilar metals joined together and producing a current between them when the junction is heated is:
  • A point contact type transistor
  • Correct Answer
    A thermocouple
  • A junction contact type transistor
  • A solenoid

Two dissimilar metals joined together and producing a current between them when the junction is heated is:

(B). A thermocouple

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Waveguides:
  • A type of transmission line
  • Hollow rectangular or circular pipe
  • Fine application as transmission lines
  • Correct Answer
    All of the above

Waveguides:

(D). All of the above

  • A type of transmission line
  • Hollow rectangular or circular pipe
  • Fine application as transmission lines

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Transistors may be compared to a conventional triode vacuum tube functionally:
  • Emitter corresponds to the cathode
  • Collector corresponds to the plate
  • Base corresponds to the grid
  • Correct Answer
    All of the above

Transistors may be compared to a conventional triode vacuum tube functionally:

(D). All of the above

  • Emitter corresponds to the cathode
  • Collector corresponds to the plate
  • Base corresponds to the grid

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Types of transistors:
  • Point-contact
  • Junction
  • Correct Answer
    Both A & B
  • NPP

Types of transistors:

(C). Both A & B

  • Point-contact
  • Junction

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When using and storing crystal microphones:
  • They should be protected from shock and vibration
  • They should be protected from humidity
  • They should be protected from high temperatures
  • Correct Answer
    All of the above

When using and storing crystal microphones:

(D). All of the above

They should be protected from:

  • shock and vibration
  • humidity
  • high temperatures

For more info, please see Sweetwater site article on
How to Take Care of Your Microphones

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What effect does a change in the dielectric constant of a capacitor dielectric material have upon the capacitance of a capacitor:
  • Correct Answer
    Capacity varies directly with the dielectric constant
  • Capacity may fluctuate wildly
  • There is no effect upon the capacitance
  • None of the above

What effect does a change in the dielectric constant of a capacitor dielectric material have upon the capacitance of a capacitor:

(A). Capacity varies directly with the dielectric constant

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Increasing the number of plates of a capacitor:
  • Correct Answer
    Will increase the capacitance
  • Will decrease the capacitance
  • Will have no effect on the capacitance
  • Will make the capacitance fluctuate

Increasing the number of plates of a capacitor:

(A). Will increase the capacitance

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If the dielectric constants of a capacitor dielectric material between the capacitor plates were changed from 1 to 1:
  • Correct Answer
    The capacitance would be twice its original value
  • The capacitance would be half its original value
  • The capacitance would decay rapidly
  • None of the above

If the dielectric constants of a capacitor dielectric material between the capacitor plates were changed from 1 to 1:

(A). The capacitance would be twice its original value

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Contacts which slide together on opening and closing:
  • Are butt joined
  • Are known as self-wiping
  • Keep the contacts clean by their action
  • Correct Answer
    B & C

Contacts which slide together on opening and closing:

(D). B & C

  • Are known as self-wiping

  • Keep the contacts clean by their action

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Permanent magnets used in head telephones:
  • Place the diaphragms under tension so that the sensitivity of the telephones will be increased
  • Improve the frequency response
  • Prevents production of second harmonics in the telephones
  • Correct Answer
    All of the above

Permanent magnets used in head telephones:

(D). All of the above

  • Place the diaphragms under tension so that the sensitivity of the telephones will be increased

  • Improve the frequency response

  • Prevents production of second harmonics in the telephones

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Emergency repairs to an inductance coil having burned or charred insulation:
  • Correct Answer
    Are generally impractical, short of rewinding the coil with good wire
  • Are always practical if repaired by coating the bad turns with insulating varnish
  • A & B
  • None of the above

Emergency repairs to an inductance coil having burned or charred insulation:

(A). Are generally impractical, short of rewinding the coil with good wire

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Indications of a defective vacuum tube in a transmitter:
  • Gas blow within the tube, excessive plate color due to overheating
  • No light from the filament, insufficient plate current, reduced output
  • Excessive plate current, possible internal arcing, fluctuating plate or grid current
  • Correct Answer
    All of the above

Indications of a defective vacuum tube in a transmitter:

(D). All of the above

  • Gas blow within the tube, excessive plate color due to overheating

  • No light from the filament, insufficient plate current, reduced output

  • Excessive plate current, possible internal arcing, fluctuating plate or grid current

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The breakdown voltage rating of a capacitor are determined by:
  • The type of dielectric material used
  • The thickness of the dielectric material
  • Correct Answer
    A & B
  • None of the above

The breakdown voltage rating of a capacitor are determined by:

(C). A & B

  • The type of dielectric material used

  • The thickness of the dielectric material

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Crystal surfaces should be free of dirt of grease to operate properly:
  • Do not touch the faces of the crystal with the fingers
  • Clean the faces with soap and water
  • Clean the faces with carbon tetrachloride
  • Correct Answer
    All of the above

Crystal surfaces should be free of dirt of grease to operate properly:

(D). All of the above

  • Do not touch the faces of the crystal with the fingers
  • Clean the faces with soap and water
  • Clean the faces with carbon tetrachloride

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A purplish glow from within a tube indicates:
  • A soft tube
  • A hard tube
  • Air or undesired gases within the tube
  • Correct Answer
    A & C

A purplish glow from within a tube indicates:

(D). A & C

  • A soft tube

  • Air or undesired gases within the tube

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Given a solenoid with a resistance of 5 ohms and 0.34 through the winding when 1108 at 60 Hz is applied. What is the impedance?
  • Correct Answer
    367 ohms
  • 350 ohms
  • 360 ohms
  • None of the above

Given a solenoid with
a resistance of 5 ohms and
0.34 through the winding when 1108
at 60 Hz is applied.
What is the impedance?

(A). 367 ohms

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Use of a low pass filter network:
  • Ripple filter in power supplies, harmonic suppression filters in antenna systems
  • Line noise filters, tone control systems
  • Crossover networks, output filters of detector circuits
  • Correct Answer
    All of the above

Use of a low pass filter network:

(D). All of the above

  • Ripple filter in power supplies, harmonic suppression filters in antenna systems

  • Line noise filters, tone control systems

  • Crossover networks, output filters of detector circuits

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A special type of power supply filter choke whose inductance is inversely proportioned to values of DC within specified limits is:
  • Smoothing choke
  • Correct Answer
    Swinging choke
  • Radio frequency choke
  • Audio frequency choke

A special type of power supply filter choke whose inductance is inversely proportioned to values of DC within specified limits is:

(B). Swinging choke

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The best suited material for use as an antenna strain insulator exposed to the elements:
  • Correct Answer
    Glazed porcelain
  • Glass
  • Graphite composite
  • Rubber

The best suited material for use as an antenna strain insulator exposed to the elements:

(A). Glazed porcelain

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Materials frequently used for relay contacts:
  • Tungsten
  • Silver
  • Gold
  • Correct Answer
    All of the above

Materials frequently used for relay contacts:

(D). All of the above

  • Tungsten
  • Silver
  • Gold

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Why is rosin used as a soldering flux?
  • It is noncorrosive
  • It allows a perfect soldering bond to be made
  • It possesses good insulation qualities
  • Correct Answer
    All of the above

Why is rosin used as a soldering flux?

(D). All of the above

  • It is non corrosive
  • It allows a perfect soldering bond to be made
  • It possesses good insulation qualities

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What substance is the most widely used in crystal oscillators?
  • Correct Answer
    Quartz
  • Galena
  • Silicon
  • Tourmaline

What substance is the most widely used in crystal oscillators?

(A). Quartz

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Why is an oscillator crystal operated at a constant temperature?
  • Just because, stupid!
  • Correct Answer
    To maintain a constant frequency output from the oscillator
  • Constant temperature allows easier frequency change
  • None of the above

Why is an oscillator crystal operated at a constant temperature?

(B). To maintain a constant frequency output from the oscillator

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The advantage of a single-button carbon microphone:
  • High output voltage
  • Sensitivity
  • Low cost
  • Correct Answer
    All of the above

The advantage of a single-button carbon microphone:

(D). All of the above

  • High output voltage
  • Sensitivity
  • Low cost

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A carbon microphone should not be:
  • Jarred while in operation
  • Tapped while in operation
  • Subjected to violent sound intensities
  • Correct Answer
    All of the above

A carbon microphone should not be:

(D). All of the above

  • Jarred while in operation
  • Tapped while in operation
  • Subjected to violent sound intensities

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In connecting head telephones directly in the plate circuit of a vacuum tube one should observe the proper polarity:
  • Correct Answer
    To maintain maximum sensitivity in the headphones
  • So its current flows opposed to the field strength of the permanent magnet
  • A & B
  • None of the above

In connecting head telephones directly in the plate circuit of a vacuum tube one should observe the proper polarity:

(A). To maintain maximum sensitivity in the headphones

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What should the plate current do in the operation of a Class B audio amplifier?
  • Correct Answer
    Fluctuate
  • Remain Steady
  • Increase
  • None of the above

What should the plate current do in the operation of a Class B audio amplifier?

(A). Fluctuate

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What turns ratio does a transformer need to match a source impedance of 500 ohms to a load of 10 ohms?
  • Correct Answer
    7.1 to 1
  • 7 to 1
  • 14 to 1
  • None of the above

What turns ratio does a transformer need to match a source impedance of 500 ohms to a load of 10 ohms?

(A). 7.1 to 1

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What microphones have a high impedance output?
  • Crystal
  • Dynamic
  • Correct Answer
    Any
  • None of the above

What microphones have a high impedance output?

(C). Any

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How may low impedance (75 ohm) head telephones be connected to the output of a vacuum tube?
  • By using an impedance matching transformer in the output stage
  • Connect them as a cathode bias resistor in the output stage
  • Correct Answer
    Either A or B
  • None of the above

How may low impedance (75 ohm) head telephones be connected to the output of a vacuum tube?

(C). Either A or B

  • By using an impedance matching transformer in the output stage

  • Connect them as a cathode bias resistor in the output stage

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Why do headphones usually have high-impedance windings?
  • They can usually be operated without an impedance matching transformer
  • They represent a closer match to the plate load impedance for the tube delivering necessary driving power than low impedance planes
  • Correct Answer
    A & B
  • None of the above

Why do headphones usually have high-impedance windings?

(C). A & B

  • They can usually be operated without an impedance matching transformer

  • They represent a closer match to the plate load impedance for the tube delivering necessary driving power than low impedance planes

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A "choke" coil:
  • Offers a relatively high impedance to AC currents
  • Has a high "Q" (low RF losses)
  • Offers a low resistance to DC currents
  • Correct Answer
    All of the above

A "choke" coil:

(D). All of the above

  • Offers a relatively high impedance to AC currents
  • Has a high "Q" (low RF losses)
  • Offers a low resistance to DC currents

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Why is correct grid bias necessary for audio frequency amplifier?
  • To minimize distortion
  • To set the operating conditions for determining the class of amplifications
  • So as not to exceed the rated plate dissipation of the tube
  • Correct Answer
    All of the above

Why is correct grid bias necessary for audio frequency amplifier?

(D). All of the above

  • To minimize distortion

  • To set the operating conditions for determining the class of amplifications

  • So as not to exceed the rated plate dissipation of the tube

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When a tube is used as a Class B amplifier what portion of the excitation voltage cycle does plate current flow?
  • Correct Answer
    Slightly more than 180 degrees
  • Slightly less than 180 degrees
  • 360 degrees
  • None of the above

When a tube is used as a Class B amplifier what portion of the excitation voltage cycle does plate current flow?

(A). Slightly more than 180 degrees

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A properly operated Class A audio amplifier:
  • Correct Answer
    Produces no serious modification of the input waveform
  • Serious distortion is present
  • A & B
  • All of the above

A properly operated Class A audio amplifier:

(A). Produces no serious modification of the input waveform

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What is the main advantage obtained by using two triodes in push-pull in a Class a audio frequency amplifier?
  • Increased power output
  • Cancellation of even harmonic distortion in the output
  • Elimination of DC saturation, elimination of cathode by-pass capacitor
  • Correct Answer
    All of the above

What is the main advantage obtained by using two triodes in push-pull in a Class a audio frequency amplifier?

(D). All of the above

  • Increased power output

  • Cancellation of even harmonic distortion in the output

  • Elimination of DC saturation, elimination of cathode by-pass capacitor

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What is the maximum permissible RMS value of audio voltage which can be applied to the grid of a Class A audio amplifier which has a grid bias of 10 V?
  • Correct Answer
    7.07 V
  • 8 V
  • 10 V
  • 14.14 V

What is the maximum permissible RMS value of audio voltage which can be applied to the grid of a Class A audio amplifier which has a grid bias of 10 V?

(A). 7.07 V

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Distortion in a Class A amplifier can be caused by:
  • Insufficient plate and screen potentials, incorrect grid bias defective rube
  • Leaky or shorted input coupling capacitor
  • Excessive anokutyde if grid signal, incorrect value of load impedance
  • Correct Answer
    All of the above

Distortion in a Class A amplifier can be caused by:

(D). All of the above

  • Insufficient plate and screen potentials, incorrect grid bias defective rube

  • Leaky or shorted input coupling capacitor

  • Excessive anokutyde if grid signal, incorrect value of load impedance

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Vacuum tubes operating as Class A amplifiers may be used as:
  • Audio power amplifiers, audio voltage amplifiers, microphones amplifiers, line amplifiers
  • Oscilloscope amplifiers, modulators
  • Phonograph amplifiers
  • Correct Answer
    All of the above

Vacuum tubes operating as Class A amplifiers may be used as:

(D). All of the above

  • Audio power amplifiers, audio voltage amplifiers, microphones amplifiers, line amplifiers
  • Oscilloscope amplifiers, modulators
  • Phonograph amplifiers

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Why is a push-pull audio frequency amplifier preferable to a single-tube stage?
  • Correct Answer
    When compared with a single-tube stage, power output is doubled
  • When compared with a single-tube stage, power output is the same
  • When compared with a single-tube stage, power output is cut in half
  • None of the above

Why is a push-pull audio frequency amplifier preferable to a single-tube stage?

(A). When compared with a single-tube stage, power output is doubled

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What is the DC plate voltage of a resistance-coupled amplifier state with a plate-supply voltage of 260 V, a plate current of 1 mA, and a plate load resistance of 100,000 ohms?
  • Correct Answer
    160 V
  • 100 V
  • 200 V
  • 60 V

What is the DC plate voltage of a resistance-coupled amplifier state with
a plate-supply voltage of 260 V,
a plate current of 1 mA, and
a plate load resistance of 100,000 ohms?

(A). 160 V

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Why is it necessary to use two tubes in a Class B audio amplifier?
  • Correct Answer
    To prevent the excessive distortion which would result from the use of only one tube in Class B
  • To eliminate hum
  • A & B
  • None of the above

Why is it necessary to use two tubes in a Class B audio amplifier?

(A). To prevent the excessive distortion which would result from the use of only one tube in Class B

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If the coupling capacitor leaked in a resistance-coupled audio frequency amplifier:
  • Excessive plate current would result
  • A large value of grid current would result
  • There would be extreme distortion, and very low gain
  • Correct Answer
    All of the above

If the coupling capacitor leaked in a resistance-coupled audio frequency amplifier:

(D). All of the above

  • Excessive plate current would result

  • A large value of grid current would result

  • There would be extreme distortion, and very low gain

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A vacuum tube operated Class C audio amplifier is not feasible, either in single or push-pull:
  • Since the plate current only flows 120 degrees, even in push-pull, only 2/3 of the cycle is reproduced and the resultant distortion would be unacceptable for audio
  • Tank circuits, which replace the missing portions of the cycle, can't be used in an audio amplifier because they only operate on one frequency
  • Correct Answer
    A & B
  • None of the above

A vacuum tube operated Class C audio amplifier is not feasible, either in single or push-pull:

(C). A & B

  • Since the plate current only flows 120 degrees, even in push-pull, only 2/3 of the cycle is reproduced and the resultant distortion would be unacceptable for audio

  • Tank circuits, which replace the missing portions of the cycle, can't be used in an audio amplifier because they only operate on one frequency

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Even harmonics may be reduced in the output of an audio frequency amplifier:
  • By operating the state push-pull
  • In a single tube amplifier, by operating the stage only on the linear part of the tube's characteristic curve
  • Correct Answer
    A & B
  • None of the above

Even harmonics may be reduced in the output of an audio frequency amplifier:

(C). A & B

  • By operating the state push-pull

  • In a single tube amplifier, by operating the stage only on the linear part of the tube's characteristic curve

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The main advantage of a tuned audio frequency amplifier in a receiver used for the reception of CW:
  • Correct Answer
    A reduction in interference from unwanted signals
  • The desired audio beat frequency is attenuates
  • A & B
  • None of the above

The main advantage of a tuned audio frequency amplifier in a receiver used for the reception of CW:

(A). A reduction in interference from unwanted signals

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Decoupling networks in the plate circuit of a multistage audio amplifier:
  • Correct Answer
    Prevents oscillations from occurring in the amplifier
  • Result in oscillations in the amplifier
  • Allow variable oscillations in the amplifier
  • None of the above

Decoupling networks in the plate circuit of a multistage audio amplifier:

(A). Prevents oscillations from occurring in the amplifier

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An audio-transformer is seldom used as the output device in the plate circuit of a tetrode audio-amplifier stage:
  • Correct Answer
    Because an ordinary transformer cannot supply enough impedance to the plate circuit
  • Because an ordinary transformer supplies too much impedance to the plate circuit
  • Because an ordinary transformer would be too costly
  • None of the above

An audio-transformer is seldom used as the output device in the plate circuit of a tetrode audio-amplifier stage:

(A). Because an ordinary transformer cannot supply enough impedance to the plate circuit

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The chief advantage of Class A audio operation is compared to the other classes of audio-frequency amplifiers:
  • Hum currents are in phase
  • Correct Answer
    Low distortion of the output signal
  • Tendency for regeneration is increased
  • Elimination of cathode bypass capacitors

The chief advantage of Class A audio operation is compared to the other classes of audio-frequency amplifiers:

(B). Low distortion of the output signal

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Which is not the principle advantage of transformer coupling compared to resistance coupling in audio-frequency amplifiers?
  • Greater gain per stage
  • Can provide necessary impedance matching
  • A & B
  • Correct Answer
    A transformer is expensive, heavy, and bulky

Which is not the principle advantage of transformer coupling compared to resistance coupling in audio-frequency amplifiers?

(D). A transformer is expensive, heavy, and bulky

Transformers are used to move electricity between coils. It can increase, decrease, or change AC to DC. When electricity moves, it creates magnetic field.

For more info, please see Wikipedia's article on Transformer, and also Inductive coupling.

Also, Elprocus site for article on What is Transformer Coupled Amplifier and Its Working

A comprehensive info on ScienceDirect site article on Coupling Transformer, which includes info on digital audio productions.

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Efficiency of a power transformer is determined by:
  • Eddy current losses
  • Hysteresis losses
  • Copper losses
  • Correct Answer
    All of the above

Efficiency of a power transformer is determined by:

(D). All of the above

  • Eddy current losses
  • Hysteresis losses
  • Copper losses

For detailed info, please see Elprocus site article on What is the Efficiency of Transformer & Its Derivation

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The ratios of primary and secondary currents in a power transformer:
  • Are approximately in inverse ratio to the turns ratio
  • Is to some extent affected by the diameter of the primary and secondary wire
  • The current ratio is in inverse proportion to the voltage ratio
  • Correct Answer
    All of the above

The ratios of primary and secondary currents in a power transformer:

(D). All of the above

  • Are approximately in inverse ratio to the turns ratio
  • Is to some extent affected by the diameter of the primary and secondary wire
  • The current ratio is in inverse proportion to the voltage ratio

For more info, please see Wikipedia's article on Transformer, and also Inductive coupling.

Also, Elprocus site for article on What is Transformer Coupled Amplifier and Its Working

A comprehensive info on ScienceDirect site article on Coupling Transformer, which includes info on digital audio productions.

For detailed info, please see Elprocus site article on What is the Efficiency of Transformer & Its Derivation

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A transformer has a primary voltage of 100, primary turns = 200, and secondary turns = 40. What is the secondary voltage?
  • Correct Answer
    20 V
  • 240 V
  • 140 V
  • 340 V

A transformer has a
primary voltage of 100,
primary turns = 200, and
secondary turns = 40.
What is the secondary voltage?

(A). 20 V

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What factors determine the no-load voltage ratio of a power transformer?
  • Power ratio
  • Correct Answer
    Turns ratio
  • Voltage ratio
  • Power factor

What factors determine the no-load voltage ratio of a power transformer?

(B). Turns ratio.

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The turns ratio of a transformer varies:
  • Correct Answer
    As the square root of the impedance ratio
  • As the square of the impedance ratio
  • As one-half the impedance ratio
  • As twice the impedance ratio

The turns ratio of a transformer varies:

(A). As the square root of the impedance ratio

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Primary cells:
  • Can be recharged
  • Cannot be recharged
  • An attempt to recharge it would not restore the eroded electrode
  • Correct Answer
    B & D

Primary cells:

(D). B & D

THIS IS A MISPRINT: The FCC Pool shows
D
Primary cells:
A..Can be recharged
B..Cannot be recharged
C..An attempt to recharge it would not restore the eroded electrode.
.B & D

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Secondary cells:
  • Can be recharged
  • Cannot be recharged
  • The products of the chemical change are not soluble in the electrolyte
  • Correct Answer
    A & C

Secondary cells:

(D). A & C

  • Can be recharged

  • The products of the chemical change are not soluble in the electrolyte

For more info, see Wikipedia's article
History of the battery, article on
Battery nomenclature, and article
List of battery sizes

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The formation of hydrogen gas around the positive electrode of a primary cell is:
  • Depolarization
  • Correct Answer
    Polarization
  • Manganese dioxide
  • None of the above

The formation of hydrogen gas around the positive electrode of a primary cell is:

(B). Polarization

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A dry cell may be tested:
  • Must be tested under normal load condition
  • May be tested under no load condition
  • May be taken by any conventional voltmeter
  • Correct Answer
    A & C

A dry cell may be tested:

(D). A & C

  • Must be tested under normal load condition

  • May be taken by any conventional voltmeter

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In the usual type dry cell:
  • The negative electrode is made of zinc
  • The positive electrode is made of carbon
  • The negative electrode is made of zinc
  • Correct Answer
    A & B

In the usual type dry cell:

(D). A & B

  • The negative electrode is made of zinc

  • The positive electrode is made of carbon

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"A", "B", and "C" batteries are alike, but specifically constructed for a particular function. Explain:
  • "B" battery is for plate and screen power
  • "C" battery for grid bias voltage
  • "A" battery for filament power
  • Correct Answer
    All of the above

"A", "B", and "C" batteries are alike, but specifically constructed for a particular function. Explain:

(D). All of the above

  • "B" battery is for plate and screen power
  • "C" battery for grid bias voltage
  • "A" battery for filament power

The batteries in "the old days" were categorized by size and type. The A battery was the smallest, then B, C, and D. They were used for portable tube (valve) radios made before transistor radios.

The "A" type battery did power filaments, with a voltage from 1.5 Volts to 9 Volts.

The "B" type battery was used to power portable tube (valve) radios, with a from 22.5 Volts to about 90 Volts. For more info, see Medium site article What Happened to “B” Batteries?

The "C" type battery provided grid bias voltage to the control the grid. Since the tube (valve) grids did not use electric current, the grid bias voltage did not deplete the charge. For more info, please see Wikipedia's article C battery

Also, great overall info is on Wikipedia's article List of battery sizes and Vacuum tube battery

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The condition of a dry "B" battery may be determined:
  • By measuring the voltage under normal load
  • By measuring the voltage under no load
  • A loss of 20 % of the voltage under normal load indicates that the battery should be replaced
  • Correct Answer
    A & C

The condition of a dry "B" battery may be determined:

(D). A & C

  • By measuring the voltage under normal load

  • A loss of 20 % of the voltage under normal load indicates that the battery should be replaced

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Spare "B" batteries should be stored:
  • Correct Answer
    In a dry place
  • In a hot place
  • Anywhere
  • A & C

Spare "B" batteries should be stored:

(A). In a dry place

For more info, please see WikiHow site article on How to Store Batteries

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A means of comparing the weight of a volume of liquid with the same volume of distilled water:
  • Correct Answer
    Specific gravity
  • Specific mass
  • Specific volume
  • None of the above

A means of comparing the weight of a volume of liquid with the same volume of distilled water:

(A). Specific gravity

Specific gravity is the ratio of the substance as compared to the same volume of water. If a substance has a specific density of 5, it means that it is 5 times as dense as the water. A number less than 1 indicates a substance less dense than water.

For more info, please see Wikipedia's article on Relative density

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Edison type batteries:
  • Have plates up nickel
  • Have plates of iron
  • Have plates of compounds of nickel and iron
  • Correct Answer
    All of the above

Edison type batteries:

(D). All of the above

Have plates:

  • up nickel
  • of iron
  • of compounds of nickel and iron

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The electrolyte of a lead-acid storage cell:
  • Concentrated sulfuric acid
  • Dilute sulfuric acid
  • Has a specific gravity about 1.3 fully charged
  • Correct Answer
    B & C

The electrolyte of a lead-acid storage cell:

(D). B & C

  • Dilute sulfuric acid
  • Has a specific gravity about 1.3 fully charged

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The negative plate of a lead-acid storage cell:
  • Correct Answer
    Is composed of pure spongy lead
  • Is composed of lead peroxide
  • Is composed of a compound of pure spongy lead and lead peroxide
  • None of the above

The negative plate of a lead-acid storage cell:

(A). Is composed of pure spongy lead

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The positive plate of a lead-acid storage cell:
  • Is composed of pure spongy lead
  • Correct Answer
    Is composed of lead peroxide
  • Is composed of a compound of pure spongy lead and lead peroxide
  • None of the above

The positive plate of a lead-acid storage cell:

(B). Is composed of lead peroxide

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The chemical composition of the electrolyte in an Edison-type storage cell:
  • Is contained in a nickel-plated sheet steel tank
  • Has a specific gravity of about 1.200
  • Is a 21% solution of potassium and lithium hydroxides in distilled water
  • Correct Answer
    All of the above

The chemical composition of the electrolyte in an Edison-type storage cell:

(D). All of the above

  • Is contained in a nickel-plated sheet steel tank
  • Has a specific gravity of about 1.200
  • Is a 21% solution of potassium and lithium hydroxides in distilled water

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The negative plate of an Edison-type storage cell is:
  • Correct Answer
    Finely powdered pure iron
  • Green oxide of nickel
  • Potassium oxide
  • None of the above

The negative plate of an Edison-type storage cell is:

(A). Finely powdered pure iron

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The positive plate of an Edison-type storage cell is:
  • Finely powdered pure iron
  • Correct Answer
    Green oxide of nickel
  • Lithium oxide
  • None of the above

The positive plate of an Edison-type storage cell is:

(B). Green oxide of nickel

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The average fully-charged voltage of an Edison storage cell is:
  • Correct Answer
    1.2 V
  • 1.5 V
  • 2 V
  • 1 V

The average fully-charged voltage of an Edison storage cell is:

(A). 1.2 V

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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Decrease in capacity of an Edison-type storage cell can be caused by:
  • Frequent overheating, and operating conditions over 115 degrees fahrenheit
  • Charging at less than the normal rate
  • Adding impure water to the electrolyte, or a weak or aged electrolyte
  • Correct Answer
    All of the above

Decrease in capacity of an Edison-type storage cell can be caused by:

(D). All of the above

  • Frequent overheating, and operating conditions over 115 degrees fahrenheit

  • Charging at less than the normal rate

  • Adding impure water to the electrolyte, or a weak or aged electrolyte

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The average fully charged voltage of a lead-acid cell is:
  • 1.0 V
  • 1.56 V
  • Correct Answer
    2.06 V
  • 2.5 V

The average fully charged voltage of a lead-acid cell is:

(C). 2.06 V

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To increase the power output of a storage cell:
  • Correct Answer
    Low internal resistance is desirable
  • High internal resistance is desirable
  • Low terminal voltage under load is desirable
  • None of the above

To increase the power output of a storage cell:

(A). Low internal resistance is desirable

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The condition of charge of an Edison cell can be determined:
  • By reading the terminal voltage under load
  • By checking the voltage against a standard discharge curve
  • Correct Answer
    Both A & B
  • Checking the specific gravity

The condition of charge of an Edison cell can be determined:

(C). Both A & B

  • By reading the terminal voltage under load

  • By checking the voltage against a standard discharge curve

For more info, see Wikipedia's article on Nickel–iron battery

Also, see Iron Edison site article on Nickel Iron (Ni-Fe) Battery

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The charge of a lead-acid storage cell:
  • May be determined by hydrometer readings
  • By measuring voltage under a heavy load
  • Correct Answer
    A or B
  • None of the above

The charge of a lead-acid storage cell:

(C). A or B

  • May be determined by hydrometer readings
    OR
  • By measuring voltage under a heavy load

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Sulfation:
  • Reduces terminal voltage
  • Increases internal resistance
  • Reduces power output
  • Correct Answer
    All of the above

Sulfation:

(D). All of the above

  • Reduces terminal voltage
  • Increases internal resistance
  • Reduces power output

The lead plates of batteries allow the accumulation of lead sulfate crystals on the surface of the plates and in surface pores. This is called "sulfation."

If there is a substantial amount of sulfate crystal accumulation, the performance of the battery is degraded.

For more info, see Crown Battery's site article on What is a Sulfated Battery and How to Prevent It

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If the polarity is reversed when charging a storage cell:
  • No damage in a lead-acid cell unless excessive
  • Damage in an Edison-cell
  • No damage in an Edison-cell if temperatures below 115 degrees Fahrenheit
  • Correct Answer
    A & C

If the polarity is reversed when charging a storage cell:

(D). A & C

  • No damage in a lead-acid cell unless excessive

  • No damage in an Edison-cell if temperatures below 115 degrees Fahrenheit

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You may measure the voltage of a battery under heavy load:
  • Correct Answer
    To determine its condition of charge
  • To determine its polarity
  • To determine its age
  • None of the above

You may measure the voltage of a battery under heavy load:

(A). To determine its condition of charge

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If the voltage of some cells in a battery are found to be reversed, what is indicated?
  • Correct Answer
    Polarity was reversed while charging
  • Polarity was doubled while charging
  • Polarity has no influence of charging
  • Polarity was correct while charging

If the voltage of some cells in a battery are found to be reversed, what is indicated?

(A). Polarity was reversed while charging

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Distilled water should be added to a lead-acid storage cell:
  • To keep the electrolyte 1/4 inch above the to of the plates
  • To keep the useful plate area sufficient to maintain the full capacity of the cell
  • None of the above
  • Correct Answer
    A & B

Distilled water should be added to a lead-acid storage cell:

(D). A & B

  • To keep the electrolyte 1/4 inch above the to of the plates -

  • To keep the useful plate area sufficient to maintain the full capacity of the cell

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Local action in a lead-acid storage cell:
  • Causes a slow discharge in the cell
  • Forms a very hard sulfate on the plates
  • May be reduced by trickle charging when the battery is not in actual use
  • Correct Answer
    All of the above

Local action in a lead-acid storage cell:

(D). All of the above

  • Causes a slow discharge in the cell
  • Forms a very hard sulfate on the plates
  • May be reduced by trickle charging when the battery is not in actual use

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To maintain a group of storage cells in good operating condition:
  • Observe correct charge and discharge rates
  • Overcharge about once a month to remove sulfation
  • Keep all terminal corrections clean and tight
  • Correct Answer
    All of the above

To maintain a group of storage cells in good operating condition:

(D). All of the above

  • Observe correct charge and discharge rates
  • Overcharge about once a month to remove sulfation
  • Keep all terminal corrections clean and tight

Battery corrosion can result from:

  • Battery electrolyte leakage due to physical damage.

  • Filling up the battery with too much water.

  • Copper connections may cause copper sulfate to corrode battery terminal stems.

  • When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.

  • The useful life of battery expiration

Clean corroded terminal stems with:

  • Baking soda with water
  • Drinking soda, such as colas.
  • Metal whisk brushes

Prevent corrosion by applying:

  • Anti-corrosion spray
  • Grease, such as petroleum jelly, or synthetic
  • Battery-specific grease

For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it

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What may cause the plates of a lead-acid call to buckle?
  • Excessive sulfation
  • Overheating
  • Overdischarging of the battery
  • Correct Answer
    All of the above

What may cause the plates of a lead-acid call to buckle?

(D). All of the above

  • Excessive sulfation
  • Overheating
  • Over discharging of the battery

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What may cause sulfation of a lead-acid cell?
  • It is a normal process
  • Overdischarging
  • Local action with improper charging
  • Correct Answer
    All of the above

What may cause sulfation of a lead-acid cell?

(D). All of the above

  • It is a normal process
  • Over discharging
  • Local action with improper charging

Battery corrosion can result from:

  • Battery electrolyte leakage due to physical damage.

  • Filling up the battery with too much water.

  • Copper connections may cause copper sulfate to corrode battery terminal stems.

  • When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.

  • The useful life of battery expiration

Clean corroded terminal stems with:

  • Baking soda with water
  • Drinking soda, such as colas.
  • Metal whisk brushes

Prevent corrosion by applying:

  • Anti-corrosion spray
  • Grease, such as petroleum jelly, or synthetic
  • Battery-specific grease

For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it

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What may be used to neutralize an acid electrolyte?
  • Ammonium hydroxide
  • Baking soda
  • Washing soda
  • Correct Answer
    All of the above

What may be used to neutralize an acid electrolyte?

(D). All of the above

  • Ammonium hydroxide
  • Baking soda
  • Washing soda

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To prevent corrosion of battery terminals:
  • Correct Answer
    Occasionally clean and coat them with Vaseline or other suitable lubricants
  • Use only brass terminals
  • Use only stainless steel terminals
  • Keep battery on trickles charge

To prevent corrosion of battery terminals:

(A). Occasionally clean and coat them with Vaseline or other suitable lubricants

Battery corrosion can result from:

  • Battery electrolyte leakage due to physical damage.

  • Filling up the battery with too much water.

  • Copper connections may cause copper sulfate to corrode battery terminal stems.

  • When battery is overcharged, it can result in corrosion of terminals. Also, overcharged batteries heat up and physically expand.

  • The useful life of battery expiration

Clean corroded terminal stems with:

  • Baking soda with water
  • Drinking soda, such as colas.
  • Metal whisk brushes

Prevent corrosion by applying:

  • Anti-corrosion spray
  • Grease, such as petroleum jelly, or synthetic
  • Battery-specific grease

For more info, see Carcody site's article on Battery Terminal Corrosion: Why it happens & How to fix it

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Why should there be ventilation to the room housing a large group of storage cells?
  • To prevent gas accumulation
  • To prevent overheating
  • To prevent the terminals from shorting
  • Correct Answer
    A & B

Why should there be ventilation to the room housing a large group of storage cells?

(D). A & B

  • To prevent gas accumulation
  • To prevent overheating

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Radio equipment on which electrolyte may be used:
  • Electrolyte capacitor
  • Electrolyte rectifier
  • Electrolyte detector
  • Correct Answer
    All of the above

Radio equipment on which electrolyte may be used:

(D). All of the above

Electrolyte:

  • capacitor
  • rectifier
  • detector

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What is the effect of low temperature on the operation of a lead-acid storage battery?
  • Electrolyte may freeze and split the battery if sg too low
  • The capacity is decreased
  • Correct Answer
    A & B
  • None of the above

What is the effect of low temperature on the operation of a lead-acid storage battery?

(C). A & B

  • Electrolyte may freeze and split the battery if sg too low
  • The capacity is decreased

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What form of energy is stored in a lead-acid storage battery?
  • Correct Answer
    Chemical
  • Mechanical
  • Heat
  • Light

What form of energy is stored in a lead-acid storage battery?

(A). Chemical

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How may polarity of a storage battery be determined?
  • Voltmeter
  • Salt water method
  • Correct Answer
    A & B
  • None of the above

How may polarity of a storage battery be determined?

(C). A & B

  • Voltmeter
  • Salt water method

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A battery with a terminal voltage of 12.5 V is to be trickle-charged at a 0.5 A rate. What resistance should be connected in series with the battery to charge from a 110 V line?
  • Correct Answer
    195 ohms
  • 300 ohms
  • 95 ohms
  • None of the above

A battery with a terminal voltage of 12.5 V
is to be trickle-charged at a 0.5 A rate.
What resistance should be connected in series with the battery to charge from a 110 V line?

(A). 195 ohms

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A discharged storage battery of 3 cells has an open circuit voltage of 1.8 V per cell and an internal resistance of 0.1 ohm per cell. What voltage is needed to give an initial charging rate of 10 A?
  • Correct Answer
    8.4 V
  • 10 V
  • 15 V
  • 12.5 V

A discharged storage battery of 3 cells
has an open circuit voltage of 1.8 V per cell and
an internal resistance of 0.1 ohm per cell.

What voltage is needed to give an initial charging rate of 10 A?

(A). 8.4 V

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What capacity in amperes of storage battery is required to operate a 50 W emergency transmitter for 6 hr.? Assume a continuous transmitter load of 70% of the key-locked demand of 40 A, and an emergency light load of 1.5 A.
  • A battery rated greater than 177 amperhours
  • A battery rated at least 177 amperhours
  • Correct Answer
    A & B
  • None of the above

Assume a continuous transmitter load of 70% of the key-locked demand of 40 A,
and an emergency light load of 1.5 A.

What capacity in amperes of storage battery is required to operate a 50 W emergency transmitter for 6 hr.?

(C). A & B

A battery rated:

  • greater than 177 amperhours
  • at least 177 amperhours

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If a receiver storage A battery could not be kept charged, and maintain the required watch period, what should you do?
  • Correct Answer
    Increase the charging rate
  • Get a new battery
  • Discontinue the required watch period
  • B & C

If a receiver storage A battery could not be kept charged, and maintain the required watch period, what should you do?

(A). Increase the charging rate

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Abnormally low input power terminal voltage of a lifeboat radiotelegraph transmitter while in operation could be caused by:
  • Reversed polarity
  • Excessive overload
  • A partially discharged battery
  • Correct Answer
    B & C

Abnormally low input power terminal voltage of a lifeboat radiotelegraph transmitter while in operation could be caused by:

(D). B & C

  • Excessive overload
  • A partially discharged battery

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If a battery has 12.4 V on open circuit and 12.2 V when its charging circuit is closed:
  • Correct Answer
    Could have polarity reversed
  • Could be overloaded
  • A & B
  • None of the above

If a battery has 12.4 V on open circuit
and 12.2 V when its charging circuit is closed:

(A). Could have polarity reversed

When charging, voltage should increase.

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The tops of lead-acid batteries should be kept dry:
  • To prevent slow discharge of the battery
  • To prevent terminal overload
  • To reduce the formation of terminal corrosion
  • Correct Answer
    A & C

The tops of lead-acid batteries should be kept dry:

(D). A & C

  • To prevent slow discharge of the battery

  • To reduce the formation of terminal corrosion

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When lead-acid cells are subject to low temperatures they should:
  • To prevent freezing
  • To provide the maximum capacity
  • Correct Answer
    A & B
  • None of the above

When lead-acid cells are subject to low temperatures they should:

(C). A & B

  • To prevent freezing
  • To provide the maximum capacity

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If an electrolyte in a lead-acid storage cell becomes low due to evaporation:
  • Correct Answer
    The level should be brought to about 1/4 inch above the tops of the plates with pure water
  • The level should be brought to about 1/4 inch above the tops of the plates with tap water
  • The level should be brought to about 1/4 inch above the tops of the plates with salt water
  • None of the above

If an electrolyte in a lead-acid storage cell becomes low due to evaporation:

(A). The level should be brought to about 1/4 inch above the tops of the plates with pure water

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An Edison storage battery should not be charged at less than the manufacturer's specified rate:
  • In order that the capacity of the battery shall be maximum after charge
  • The chemical reactions of the Edison-type cell
  • Correct Answer
    A & B
  • None of the above

An Edison storage battery should not be charged at less than the manufacturer's specified rate:

(C). A & B

  • In order that the capacity of the battery shall be maximum after charge

  • The chemical reactions of the Edison-type cell

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Your emergency battery has a specific gravity reading of 1.120. What should be done?
  • Place the battery on charge at once
  • Bring the electrolyte level to about 1/4 inch above the top of the plates
  • The battery will be fully charged when the specific gravity reads 1.280 to 1.300
  • Correct Answer
    All of the above

Your emergency battery has a specific gravity reading of 1.120. What should be done?

(D). All of the above

  • Place the battery on charge at once

  • Bring the electrolyte level to about 1/4 inch above the top of the plates

  • The battery will be fully charged when the specific gravity reads 1.280 to 1.300

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What care should be taken with selecting water to add to a storage cell?
  • Correct Answer
    It should be chemically pure or distilled
  • It should be only sea water
  • Tap water is as good as any
  • None of the above

What care should be taken with selecting water to add to a storage cell?

(A). It should be chemically pure or distilled

Water is needed along with the electrolyte to take H2O and split into H and 2O when charging a lead battery. During the charging a gas is released which can ignite, so marine batteries need to be vented. Also, water is lost, requiring additional watering of the battery. Water without any other mineral elements is a must. Never use tap water, as the minerals in it will reduce the capacity of the battery and increase charging time.

For detail info, please see Progressive Dynamics, Inc.'s article on Battery Basics

Also, look at West Marine site, article on How to Select a Marine Battery

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If the circuit breakers refuse to stay closed when you place the emergency batteries on charge, what is the trouble?
  • Internally shorted cells
  • Reversed charging polarity
  • Grounded circuit connections
  • Correct Answer
    Any of the above

If the circuit breakers refuse to stay closed when you place the emergency batteries on charge, what is the trouble?

(D). Any of the above

  • Internally shorted cells
  • Reversed charging polarity
  • Grounded circuit connections

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Heat developed within a storage cell under charge or discharge conditions is caused by:
  • I2R losses
  • Energy transfer due to chemical reactions
  • Correct Answer
    A & B
  • None of the above

Heat developed within a storage cell under charge or discharge conditions is caused by:

(C). A & B

  • I2R losses

  • Energy transfer due to chemical reactions

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How would you connect a group of similar cells in a storage battery to obtain the maximum zero resistance current?
  • Correct Answer
    In parallel
  • In series
  • In series/parallel
  • None of the above

How would you connect a group of similar cells in a storage battery to obtain the maximum zero resistance current?

(A). In parallel

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How would you connect a group of similar cells in a storage battery to obtain the maximum no-bond output voltage?
  • In parallel
  • Correct Answer
    In series
  • In series/parallel
  • None of the above

How would you connect a group of similar cells in a storage battery to obtain the maximum no-bond output voltage?

(B). In series

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What current will flow in a 6 V storage battery with an internal resistance of 0.01 ohms, when a 3 W, 6 V lamp is connected?
  • Correct Answer
    0.4995 A
  • 0.4885 A
  • 0.5566 A
  • 0.5795 A

What current will flow in a
6 V storage battery with
an internal resistance of 0.01 ohms,
when a 3 W, 6 V lamp is connected?

A. 0.4995 A

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The charging rate of a storage cell charged from a fixed voltage source decreases as the charging progresses opposition to the charging voltage?
  • Because as cell voltages increase, offering more opposition to the charging voltage
  • When the effective charging potential is reduced, the charging current is decreased
  • Correct Answer
    Both A & B
  • None of the above

The charging rate of a storage cell charged from a fixed voltage source decreases as the charging progresses opposition to the charging voltage?

(C). Both A & B

  • Because as cell voltages increase, offering more opposition to the charging voltage

  • When the effective charging potential is reduced, the charging current is decreased

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The principal function of the filter in a power supply:
  • To remove the variations in amplitude of the rectifier output
  • To provide a relatively unvarying DC voltage for use in the various circuits
  • Correct Answer
    Either A or B
  • None of the above

The principal function of the filter in a power supply:

(C). Either A or B

  • To remove the variations in amplitude of the rectifier output
    OR
  • To provide a relatively unvarying DC voltage for use in the various circuits

The power supply filters even out variations in flow of electrons in Direct Current circuits. There are capacitor filters and choke filters.

For more info, please see All About Circuits site article on An Introduction to Filters

Also, see Learn About Electronics Power Supplies article on Filter Circuits.

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Advantages of capacitor input and choke-input filters when used with rectifiers:
  • Capacitor-input filter provides higher output voltage under reasonably light load conditions
  • Choke-input filter offers better voltage regulations
  • Correct Answer
    A & B
  • None of the above

Advantages of capacitor input and choke-input filters when used with rectifiers:

(C). A & B

  • Capacitor-input filter provides higher output voltage under reasonably light load conditions

  • Choke-input filter offers better voltage regulations

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A high-resistance fixed resistor is shunted across each unit of a high voltage series capacitor bank in the power-supply filter circuit to:
  • Correct Answer
    Insure that the correct voltage appears across each unit
  • Discharge the capacitors
  • Does not insure the correct voltage across each unit
  • None of the above

A high-resistance fixed resistor is shunted across each unit of a high voltage series capacitor bank in the power-supply filter circuit to:

(A). Insure that the correct voltage appears across each unit

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Part of the secondary winding of a transmitters power transformer is accidentally shorted. What should be the immediate effect?
  • Correct Answer
    The current would rise to an excessive value and trip the circuit breaker
  • The short would burn the transformer
  • The current in the secondary winding would decrease
  • None of the above

Part of the secondary winding of a transmitters power transformer is accidentally shorted. What should be the immediate effect?

(A). The current would rise to an excessive value and trip the circuit breaker

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Bleeder resistors are used in power supplies:
  • To improve the output voltage regulation
  • They also discharge the filter capacitor when the power is turned off
  • Correct Answer
    Either A or B
  • None of the above

Bleeder resistors are used in power supplies:

(C). Either A or B

  • To improve the output voltage regulation
    OR
  • They also discharge the filter capacitor when the power is turned

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The ratio of the frequencies of the output and input circuits of a single-phase full-wave rectifier:
  • 1 to 1
  • Correct Answer
    2 to 1
  • 1 to 2
  • None of the above

The ratio of the frequencies of the output and input circuits of a single-phase full-wave rectifier:

(B). 2 to 1

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A capacitor is sometimes placed in series with the primary of a power transformer:
  • Correct Answer
    To improve the power factor
  • To improve output voltage regulation
  • To rectify the primary windings
  • None of the above

A capacitor is sometimes placed in series with the primary of a power transformer:

(A). To improve the power factor

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What is the maximum allowable secondary voltage of a transformer used as a center-tapped full-wave rectifier with tubes having a peak inverse voltage rating of 10,000 V?
  • Correct Answer
    7070 V
  • 14140 V
  • 10000 V
  • 5000 V

What is the maximum allowable secondary voltage of a transformer used as a center-tapped full-wave rectifier with tubes having a peak inverse voltage rating of 10,000 V?

(A). 7070 V

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If a 60 Hz transformer is connected to a 120 Hz source of the same voltage:
  • The impedance of the transformers would be greater
  • The current would be reduced
  • There would be a decrease in power delivered to the load
  • Correct Answer
    All the above

If a 60 Hz transformer is connected to a 120 Hz source of the same voltage:

(D). All the above

  • The impedance of the transformers would be greater

  • The current would be reduced

  • There would be a decrease in power delivered to the load

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If a 500 Hz transformer is connected to a 60 Hz source of the same voltage:
  • The primary would draw excessive current
  • The transformer would overheat
  • The primary might burn out
  • Correct Answer
    All of the above

If a 500 Hz transformer is connected to a 60 Hz source of the same voltage:

(D). All of the above

  • The primary would draw excessive current

  • The transformer would overheat

  • The primary might burn out

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A 500 Hz AC plate supply, rectified by a full-wave, unfiltered rectifier circuit. What would the emission be?
  • A modulated continuous wave of 500 Hz
  • A modulated continuous wave of 1000 Hz
  • A-2
  • Correct Answer
    All of the above

A 500 Hz AC plate supply, rectified by a full-wave, unfiltered rectifier circuit. What would the emission be?

(D). All of the above

  • A modulated continuous wave of 500 Hz

  • A modulated continuous wave of 1000 Hz

  • A-2

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The purpose of an air gap in a filter choke coil core. Which is the incorrect answer?
  • Correct Answer
    To decrease the effective inductance for the AC component of current by increasing the DC saturation
  • To increase the effective inductance for the AC component of current by decreasing the DC saturation
  • The inductance of the coil in general's decreased
  • All of the above

The purpose of an air gap in a filter choke coil core. Which is the incorrect answer?

(A). To decrease the effective inductance for the AC component of current by increasing the DC saturation

The purpose includes:

  • To increase the effective inductance for the AC component of current by decreasing the DC saturation

  • The inductance of the coil in general's decreased

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Loose laminations in a filter choke:
  • Make it impossible to firmly connect the choke in a circuit
  • A & C
  • Correct Answer
    Cause a buzzing or chattering sound
  • None of the above

Loose laminations in a filter choke:

(C). Cause a buzzing or chattering sound

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Poor regulation in a power supply may be caused by:
  • No bleeder resistance
  • High resistance filter chokes
  • Insufficient filter capacity
  • Correct Answer
    All of the above

Poor regulation in a power supply may be caused by:

(D). All of the above

  • No bleeder resistance

  • High resistance filter chokes

  • Insufficient filter capacity

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Why should the case of a high-voltage transformer be grounded?
  • To protect personnel handling the equipment from shock
  • To prevent high static voltages building up between the case and grounds
  • Correct Answer
    A & B
  • None of the above

Why should the case of a high-voltage transformer be grounded?

(C). A & B

  • To protect personnel handling the equipment from shock

  • To prevent high static voltages building up between the case and grounds

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When connecting electrolytic capacitors in series:
  • Correct Answer
    Observe the polarity marked on the component
  • There is no polarity to observe
  • Connect anode to anode
  • Connect cathode to cathode

When connecting electrolytic capacitors in series:

(A). Observe the polarity marked on the component

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Full wave rectification has ____ than half-wave:
  • Better output voltage regulation
  • Smaller filter components for a given ripple percentage
  • Correct Answer
    A and B
  • None of the above

Full wave rectification has ____ than half-wave:

(C). A and B

  • Better output voltage regulation

  • Smaller filter components for a given ripple percentage

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Voltage regulation is ____ with a high resistance choke:
  • Correct Answer
    Made worse
  • Made better
  • The same
  • None of the above

Voltage regulation is ____ with a high resistance choke:

(A). Made worse

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Electrolyte capacitors are desirable over other types because:
  • A large capacitance may be obtained with small physical dimensions
  • They have a cathode
  • The wet-type electrolytic capacitor is "self-healing"
  • Correct Answer
    A & C

Electrolyte capacitors are desirable over other types because:

(D). A & C

  • A large capacitance may be obtained with small physical dimensions

  • The wet-type electrolytic capacitor is "self-healing"

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The most common values of chokes range from:
  • Correct Answer
    5 H to 30 H
  • 30 H-100 H
  • 1 H to 100 H
  • 100 H to 1000 H

The most common values of chokes range from:

(A). 5 H to 30 H

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The power transformer and rectifier of a radio receiver are designed to supply a plate voltage of 250 V when operating from a 110 V 60 Hz supply, if the transformer is connected to 110 VDC what will happen?
  • The secondary would burn out
  • The primary would overheat and burn out
  • The circuit breaker would open to protect the circuit
  • Correct Answer
    Either A or B

The power transformer and rectifier of a radio receiver are designed to supply a plate
voltage of 250 V
when operating from a
110 V 60 Hz supply,
if the transformer is connected to 110 VDC what will happen?

(D). Either A or B

  • The secondary would burn out

  • The primary would overheat and burn out

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A shunt-wound DC motor:
  • Correct Answer
    Has a practically constant speed under widely varying load conditions
  • Has poor speed regulation under varying load conditions
  • High starting torque
  • None of the above

A shunt-wound DC motor:

(A). Has a practically constant speed under widely varying load conditions

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A series DC motor has:
  • Maximum torque at low speed
  • Quick starting
  • Poor speed regulation under varying loads
  • Correct Answer
    All of the above

A series DC motor has:

(D). All of the above

  • Maximum torque at low speed
  • Quick starting
  • Poor speed regulation under varying loads

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This partially counteracts the line voltage and so limits the armature current in a DC motor:
  • EMF
  • Correct Answer
    Counter EMF
  • Opposition EMF
  • None of the above

This partially counteracts the line voltage and so limits the armature current in a DC motor:

(B). Counter EMF

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A compound-wound DC motor:
  • Has constant speed under changing load conditions
  • Low starting torque
  • High starting torque
  • Correct Answer
    A & B

A compound-wound DC motor:

(D). A & B

  • Has constant speed under changing load conditions
  • Low starting torque
  • High starting torque

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Laminated iron is used in armature and field construction to:
  • Reduce eddy current losses
  • Offer a number of high-resistance paths to Eddy currents
  • Correct Answer
    A or B
  • None of the above

Laminated iron is used in armature and field construction to:

(C). A or B

  • Reduce eddy current losses
    OR
  • Offer a number of high-resistance paths to Eddy currents

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The ____ of a DC motor periodically change the armature coils to maintain one direction of rotation:
  • Field coils
  • Correct Answer
    Connector
  • Brushes
  • Auxiliary speed control

The ____ of a DC motor periodically change the armature coils to maintain one direction of rotation:

(B). Connector

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The speed of a series DC motor may increase and destroy the motor by centrifugal action:
  • Correct Answer
    When operated without a load
  • When operated on AC
  • When operated under varying load
  • None of the above

The speed of a series DC motor may increase and destroy the motor by centrifugal action:

(A). When operated without a load

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When the field of a shunt-wound DC motor opens while the machine is operating under no load:
  • Correct Answer
    The motor would race, and if unchoked, might destroy itself
  • The motor would quit running without damage
  • The motor would burn out the field coils
  • None of the above

When the field of a shunt-wound DC motor opens while the machine is operating under no load:

(A). The motor would race, and if unchoked, might destroy itself

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____ are used in a DC motor to reduce brush sparking without moving the brushes:
  • Interpoles
  • Commutating poles
  • Correct Answer
    Either A or B
  • None of the above

____ are used in a DC motor to reduce brush sparking without moving the brushes:

(C). Either A or B

  • Interpoles are used in a DC motor to reduce brush sparking without moving the brushes

  • Commutating poles are used in a DC motor to reduce brush sparking without moving the brushes

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A short in the armature coils of a DC motor causes:
  • No excessive sparking at the commutator brushes
  • No overheating of the motor
  • Correct Answer
    Reduction of speed under load, and excessive armature current
  • All of the above

A short in the armature coils of a DC motor causes:

(C). Reduction of speed under load, and excessive armature current

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The motor-field rheostat should be ____ when starting a DC motor generator set:
  • Minimum resistance in the armature circuit
  • Correct Answer
    Minimum resistance in the field circuit
  • Maximum resistance in the field circuit
  • None of the above

The motor-field rheostat should be ____ when starting a DC motor generator set:

(B). Minimum resistance in the field circuit

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If a motor generator fails to start when the start button is depressed, the trouble may be:
  • Blown fuse or tripped circuit breaker
  • Open armature or motor-field rheostat
  • Broken connections, defective brushes
  • Correct Answer
    All of the above

If a motor generator fails to start when the start button is depressed, the trouble may be:

(D). All of the above

  • Blown fuse or tripped circuit breaker

  • Open armature or motor-field rheostat

  • Broken connections, defective brushes

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When increased output is desired from a motor-generator, what is the usual procedure?
  • Correct Answer
    Decrease the resistance after rheostat in series with the generator field
  • Increase the resistance of the rheostat in series with the generator field
  • Output cannot be easily increased
  • Shut down the motor-generator and restart under full load

When increased output is desired from a motor-generator, what is the usual procedure?

(A). Decrease the resistance after rheostat in series with the generator field

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A dynamotor is:
  • A combination motor-generator which utilizes a common field winding
  • Usually run by battery power
  • A higher efficiency than a motor-generator
  • Correct Answer
    All of the above

A dynamotor is:

(D). All of the above

  • A combination motor-generator which utilizes a common field winding
  • Usually run by battery power
  • A higher efficiency than a motor-generator

The dynamotor has a single motor and generator coil with a single rotor. It can take input of a voltage that is different than the output voltage, such as DC current of low voltage input and turn it into DC current high voltage.

For more info see Wikipedia's article on Motor–generator and Instructables site's article on Reviving a WW2 Dynamotor, How Tube Radios Went Mobile During the War

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Output voltage of a dynamotor may be regulated:
  • Only by changing the speed of the motor