A unit of the reactive electric power delivered by an alternating current (AC) circuit. In an AC circuit, the electric potential or voltage (measured in volts) and the current (in amperes) alternate direction, varying smoothly according to sine curves. In a purely resistive circuit, current is in phase with voltage. In a purely inductive circuit, the variations of the current would lag the variations in the voltage by 1/4 cycle, or 90º. In real circuits, the current can be separated into two parts: a part in phase with the voltage, and the "reactive" part, which lags the voltage by 90º. The reactive part does no net work; it simply heats the conductor. Reactive current does perform important magnetizing and voltage-regulation functions in real circuits. The reactive power is the product of the voltage and the reactive part of the current. The name of the unit is an acronym for volt-ampere-reactive