Question

The instantaneous values of current and voltage in an AC circuit are given by $I=6\sin \left(100\pi t+\frac{\pi }{4}\right),$ $V=5\sin \left(100\pi t-\frac{\pi }{4}\right),$ then

• A. current leads the voltage by $45^{\circ }$
• B. voltage leads the current by $90^{\circ }$
• C. current leads the voltage by $90^{\circ }$
• D. voltage leads the current by $45^{\circ }$

Answer 1

Answer: (C)

The phase difference between instantaneous values of
$I$ and $V$ is $+\frac{\pi }{4}-\left(-\frac{\pi }{4}\right)=\frac{\pi }{2}$
Hence, current leads the voltage by $90^{\circ }$ .