Practice portal › Alternating Current › Power in AC Circuits
Asked in GUJCET 2009 · Average power and heating
Idea: in an ideal capacitor the current leads the voltage by π/2, so the phase difference is φ = 90°.
Average power P = VᵣₘₛIᵣₘₛ cos φ = VᵣₘₛIᵣₘₛ cos 90° = 0.
Physically: in one quarter cycle the capacitor charges and stores energy; in the next it discharges and returns the same energy to the source.
So the average power dissipated is zero.
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