Prove that an ideal inductor does not dissipate power in an a .c circuit.

Let us consider the e.m.f. of the AC signal of the form

Since in the inductor current lags behind e.m.f. therefore current *I* at an instant is given by

Thus power through an inductor at an instant of time

Now average power in a complete cycle

Thus average power dissipated in an ideal inductor is zero over a full AC cycle

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