Question

For a pure inductor, or a pure capacitor, connected to an a.c. voltage source, one can say that the instantnaeous power.

(1) as well as the average, over a cycle, are both zero

(2) may not be zero but the average power, over a cycle, is zero

(3) can zero but the average power, over a cycle, is hot zero

(4) as well as the average power, over a cycle, are both not zero

Answer 1

(2) may not be zero but the average power, over a cycle, is zero

The current, in a pure inductor, or a pure capacitor, has a phase lag of ±π/2 with respect to the applied voltage. 

Hence if the applied voltage is (v₀ sinωt), the current is I₀ sin (ω±π/2), is ± I₀ ωt.

The instantaneous power is, therefore,