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} $ .