What is the peak-to-peak RF voltage on the 50 ohm output of a 100 watt transmitter?

200 volts

From haihuynh8108:

\begin{align} E &= \sqrt{P \times R}\\ &= \sqrt{100\text{ watts}\times 50\text{ ohms}}\\ &= \sqrt{5,000\text{volts}}\\ \ V_{\text{RMS}} &= 70.71\text{ volts}\\ \end{align}

[B] Next, multiply the \(V_{\text{RMS}}\) by \(2\sqrt{2}\) to find the peak-to-peak voltage:
\begin{align} V_{\text{pk-pk}} &= V_{\text{RMS}} \times 2\sqrt{2}\\ &= 70.71 \times 2\sqrt{2}\\ &\approx 200 \text{ volts}\\ \end{align}

References:
Circuit Digest, "RMS Voltage Calculator"
OneChip, "RMS<->Peak<->P-P"

[Rev. B] Format modified
[Rev. C] Added reference

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What is the maximum DC or RMS voltage that may be connected across a 20 watt, 2,000 ohm resistor?

200 volts.

From wp2ahg:

\begin{align} E &= \sqrt{P \times R}\\ &= \sqrt{20\text{ watts}\times 2,000\text{ ohms}}\\ &= \sqrt{40,000\text{volts}}\\ &= 200\text{ Volts}\\ \\ \end{align}

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A 500-ohm, 2-watt resistor and a 1500-ohm, 1-watt resistor are connected in parallel.

What is the maximum voltage that can be applied across the parallel circuit without exceeding wattage ratings?

31.6 volts.

From kd7bbc:

First find the max voltage of each resistor.

\begin{align} E_1 &= \sqrt{P_1 \times R_1}\\ &= \sqrt{500 \times 2}\\ &= 31.6V\\ \\ E_2 &= \sqrt{P_2 \times R_2}\\ &= \sqrt{1500 \times 1}\\ &= 38.7V \end{align}

\(R_1\) has a lower max voltage and thus will limit the voltage to a max of \(31.6V\)

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What is the maximum rated current-carrying capacity of a resistor marked “2000 ohms, 200 watts”?

(A). 0.316 amps

From wp2ahg:

Square Root in Amperes of Power in Watts divided by Resistance in Ohms.

\begin{align} I &= \sqrt{P \div R}\\ \\ \end{align}

\begin{align} I &= \sqrt{200\text{watts}\div 2,000\text{ohms}}\\ & \ \\ &= \sqrt{0.1\text{ohms}}\\ & \ \\ &= 0.316\text{ amps} \\ \end{align}

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