Electric power is Volt-ampere. The power used by a circuit component depends on the current and the potential difference across the component. P = V × I where P is power in watts(W), V is potential difference in volts, and I is current in amperes. For example, cars auxiliary power outlets may be rated at 20 A, so that the circuit can deliver a maximum power P = IV = (20 A) (12 V) = 240 W.