A small signal voltage V(t) = V _ 0 sin is applied across an ideal capacitor C :

Correct answer: B. Over a full cycle the capacitor C does not consume any energy from the voltage source In capacitor current leads the voltage by ϕ = (π)/(2) phase. Average power dissipated in AC circuit is given by P _ av = V _ rms I _ rms (ϕ) In capacitor ϕ = (π)/(2) so ((π)/(2)) is zero.

NEET 2016

Exam: NEET
Year: 2016
Subject: Physics
Chapter: Alternating Current

NEET 2016 · Physics · Alternating Current

A small signal voltage V(t) = V _ 0 sin is applied across an ideal...

A small signal voltage

V\left(t\right) = {V}_{0}sin \omegat

is applied across an ideal capacitor

\text{C}

Options

ACurrent $I(t),$ lags voltage $V(t)$ by ${90}^{o}$
BOver a full cycle the capacitor $\text{C}$ does not consume any energy from the voltage source
CCurrent $I(t)$ is in phase with voltage $V(t).$
DCurrent $I(t)$ leads voltage $V(t)$ by ${180}^{o}$

Correct answer

B. Over a full cycle the capacitor $\text{C}$ does not consume any energy from the voltage source

Step-by-step solution

In capacitor current leads the voltage by $ϕ = \dfrac{\pi}{2}$ phase. Average power dissipated in AC circuit is given by

${P}_{av} = {V}_{rms}{I}_{rms}\cos \left(ϕ\right)$

In capacitor $ϕ = \dfrac{\pi}{2}$ so $\cos \left(\dfrac{\pi}{2}\right)$ is zero.

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