If the ac peak voltage across a 100-ohm resistor is 120 V, then the average power dissipated by the resistor is
A)102 W.
B)288 W.
C)72 W.
D)144 W.
E)220 W.

Question

Quizplus · Accepted Answer

The average power dissipated by a resistor in an AC circuit is given by P_avg = V_rms^2 / R. The RMS voltage V_rms is V_peak / √2. So, V_rms = 120 V / √2 = 84.85 V. Then, P_avg = (84.85^2) / 100 = 72 W.

If the Ac Peak Voltage Across a 100-Ohm Resistor Is