It may help to remember RESISTor as a synonym for oppose, as in oppose the flow of current

Resistor Symbol

https://en.wikipedia.org/wiki/Resistor

Remember, an inductor opposes a CHANGE in current, i.e. an alternating current (AC) - this question is only concerned about direct current (DC).

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A potentiometer (pot) can be configured as a user controlled variable resistor. This change in resistance in turn controls the volume.

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A Potentiometer is sometimes called a variable resistor; the schematic symbol looks just like a resistor (a line with a section in the middle that is jagged up and down before continuing straight), but has an arrow pointing perpendicular at the center of the symbol (at the zig-zag section). Potentiometer Symbol

Potentiometers usually have three poles, one on each side (with the total resistance of the potentiometer between them) and one in the middle which moves back and forth. The total resistance from the middle terminal to an edge is the inverse of the resistance from the middle to the other edge, meaning that as you slide, turn, or otherwise adjust the potentiometer the resistance on one side grows while the other shrinks.

Take a look at the wikipedia article for more information.

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There are two questions in the pool that are very similar; one asks about a component storing energy in an electric field, the other in a magnetic field. The electric field is a capacitor; it consists of at least two conductors separated by an insulator (or dielectric). When voltage is applied to the capacitor it will initially pull a lot of current, dropping the voltage and slowly charging up an electric field (due to the difference in potential between the positive and negative charges on the capacitor). Capacitors thus store energy in the electric field, and once they have charged up they no longer allow current to pass through.

If the power source (such as a battery) is removed, the capacitor will begin to discharge, initially keeping the circuit at exactly the same voltage as before with the current dying down until the voltage can no longer be maintained with the energy remaining in the electric field. For this reason, we say that a capacitor resists change in voltage.

Think "MICE:" "(M)agnetic field, (I)nductor. (C)apacitor, (E)lectric field.

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A Capacitor is an electrical component that stores energy in an electric field. It consists of at least two conductors separated by an insulator (or dielectric).

The schematic symbol looks just like its construction.

When voltage is applied to the capacitor it will initially pull a lot of current, dropping the voltage and slowly charging up an electric field (due to the difference in potential between the positive and negative charges on the capacitor). Capacitors thus store energy in the electric field, and once they have charged up they no longer allow current to pass through.

If the power source (such as a battery) is removed, the capacitor will begin to discharge, initially keeping the circuit at exactly the same voltage as before with the current dying down until the voltage can no longer be maintained with the energy remaining in the electric field. For this reason, we say that a capacitor resists change in voltage.

Note that this question is vague and that resistors and potentiometers could also be described similarly. It should probably be amended.

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There are two questions in the pool that are very similar; one asks about a component storing energy in an electric field, the other in a magnetic field. The magnetic field is an inductor; it generally consists of a coil of wire.

The inductor symbol looks very much like its construction.

The characteristics of the inductor vary drastically depending on whether or not the wire has a ferrite (susceptible to magnetism) core inside; if it does, the ferrite core becomes itself a magnet. This is how electromagnets are made, such as in the classic electronics experiment of wrapping insulated wire around a nail and turning it into an electromagnet.

When current is applied to an inductor, it initially resists the current's flow because of the magnetic field that is generated as the current begins to move through the coil; as the magnetic field charges up, the resistance to the current weakens until the current flows as though through a straight wire. However, when the current source is removed the magnetic field will begin to discharge, keeping the current constant for as long as it can, increasing the voltage until the energy runs out. This is why inductors (including transformers) can be used to build "shockers", or small electronic devices that can produce enough voltage to shock someone, but without enough current to injure them (but hurt them in the case of tazers). The inductor as it discharges pushes the voltage up until it can jump the gap and "spark".

If you can remember that an inductor is a coil of wire and that a coil around a nail creates an electromagnet, then you should be able to remember that an inductor stores energy in a magnetic field.

Mnemonic (memory) hint: Think of "MICE." (M)agnetic field, (I)nductor. (C)apacitor, (E)lectric field.

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An inductor generally consists of a coil of wire.

The schematic symbol looks very much like its construction.

The characteristics of the inductor vary drastically depending on whether or not the wire has a ferrite (susceptible to magnetism) core inside; if it does, the ferrite core becomes itself a magnet. This is how electromagnets are made, such as in the classic electronics experiment of wrapping insulated wire around a nail and turning it into an electromagnet.

When current is applied to an inductor, it initially resists the current's flow because of the magnetic field that is generated as the current begins to move through the coil; as the magnetic field charges up, the resistance to the current weakens until the current flows as though through a straight wire. However, when the current source is removed the magnetic field will begin to discharge, keeping the current constant for as long as it can, increasing the voltage until the energy runs out. This is why inductors (including transformers) can be used to build "shockers", or small electronic devices that can produce enough voltage to shock someone, but without enough current to really hurt them. The inductor as it discharges pushes the voltage up until it can jump the gap and "spark".

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It is easy to get mixed up on this question.

• SP = Single Pole
• DT = Double Throw

The SP means there is a single input. The DT means there are two outputs that the one input can be connected to. The switch can connect the one pole to either of two outputs. There is no third "floating" state.

The other switch types can be similarly figured out.

If the the first part is SP, then there is one input (single). If the first part is DP, there are two inputs (double).

If the second part is ST, there is only one output for each of the inputs (single). If the second part is DT, there are two outputs for each input (double).

Switches exist in all the possible combinations: SPST, SPDT, DPST, and DPDT.

A regular light switch in your home is SPST. When the SP and ST are connected, electric current can flow. The circuit is "closed." When SP and ST are disconnected, the circuit is "open" and no current flows.

A three-way light switch in your home is SPDT. The switch connects to one or the other of the two (double) traveler wires, as they are called. These traveler wires are connected to another SPDT switch so that both switches can operate the light.

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A fuse acts like a wire until excessive current flows through it. Fuses are rated in amps. It is very important to replace blown fuses with the same rating and same type (such as fast blow vs slow blow). Otherwise the protected circuit may fail catastrophically including igniting a fire.

A varactor is also called a varicap diode, varactor diode, variable capacitance diode, variable reactance diode or tuning diode.

A thyrotron is a gas filled tube used as a rectifier or a switch.

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Yes, all of these are rechargeable. A zinc-carbon battery is not.

A way to remember this is: Can't Zap a Carbon Zinc

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The chemical reactions of Carbon-zinc type batteries are not readily reversible, unlike Nickel-cadmium, lead-acid, and Lithium-ion type batteries.

A way to remember this if you have trouble is that you Can't Zap a Carbon-Zinc battery with an electric charge to recharge it!

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