AC power

This article deals with power in AC systems. See Mains electricity for information on utility supplied AC power. Power is defined as the rate of flow of energy past a given point. In alternating current circuits, energy storage elements such as inductors and capacitors  cause periodic reversals of energy flow. The portion of power flow averaged over a complete cycle of the AC waveform that results in net transfer of energy in one direction is known as real power. The portion of power flow due to stored energy which returns to the source in each cycle is known as reactive power.
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