To determine the peak power in an alternating current (AC) circuit, you need to know both the peak voltage and the resistance.

In an AC circuit, both voltage and current continuously fluctuate in direction and magnitude. The peak voltage, denoted as $V_p$, represents the maximum voltage that the circuit achieves during each cycle. Consequently, the peak power, $P$, is the highest power that the circuit can deliver within that same cycle.

To calculate the peak power, you can use the formula:

In this equation, $P$ is the peak power, $V_p$ is the peak voltage, and $R$ is the resistance of the circuit. It is essential to note that this formula is applicable only to purely resistive circuits, which means that there is no inductance or capacitance present.

If the circuit includes inductive or capacitive elements, you will need to employ a more complex formula to accurately calculate the peak power. For instance, if the circuit has inductance, the peak power can be determined using:

In this formula, $\theta$ represents the phase angle between the voltage and the current. This adjustment accounts for the effects of the circuit’s reactance on the overall power delivery.