Question

If the ac peak voltage across a 100-ohm resistor is 120 V, then the average power dissipated by the resistor is ________

Answer 1

Answer:

The average power dissipated is 72 W.

Explanation:

Given;

peak voltage of the AC circuit, V₀ = 120 V

resistance of the resistor, R = 100 -ohm

The average power dissipated by the resistor is given by;

$P_{avg} = \frac{1}{2} I_oV_o= I_{rms}V_{rms} = \frac{V_{rms}^2}{R}$

where;

$V_{rms}$ is the root-mean-square-voltage

$V_{rms} = \frac{V_o}{\sqrt{2}} \\\\V_{rms} = \frac{120}{\sqrt{2}}\\\\V_{rms} = 84.853 \ V$

The average power dissipated by the resistor is calculated as;

$P_{avg} = \frac{V_{rms}^2}{R}\\\\P_{avg} = \frac{84.853^2}{100}\\\\P_{avg} = 72 \ W$

Therefore, the average power dissipated is 72 W.