Alternating Current - Result Question 2

2. A small signal voltage $V(t)=V_0 \sin \omega t$ is applied across an ideal capacitor $C$ :

[2016]

(a) Current I (t), lags voltage V(t) by $90^{\circ}$.

(b) Over a full cycle the capacitor $C$ does not consume any energy from the voltage source.

(c) Current $I(t)$ is in phase with voltage $V(t)$.

(d) Current $I(t)$ leads voltage $V(t)$ by $180^{\circ}$.

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Answer:

Correct Answer: 2. (b)

Solution:

  1. (b) As we know, power $P=V _{rms} \cdot I _{rms} \cos \phi$ as $\cos \phi=0 \quad(\because \phi=90^{\circ})$

$\therefore \quad$ Power consumed $=0$

(in one complete cycle)