A small signal voltage V t = V 0 sin ⁡ ω t is applied across an ideal capacitor C :

A small signal voltage Vt=V0sin⁡ωt is applied across an ideal capacitor C:
  1. Current I(t), lags voltage V(t) by 90o
  2. Over a full cycle the capacitor C does not consume any energy from the voltage source
  3. Current I(t) is in phase with voltage V(t).
  4. Current I(t) leads voltage V(t) by 180o

Solution

In capacitor current leads the voltage by ϕ=π2 phase. Average power dissipated in AC circuit is given by

Pav=VrmsIrmscosϕ

In capacitor ϕ=π2 so cosπ2 is zero.

Asked in: NEET 2016 (Phase 1)

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