Question

In an A.C. circuit, the instantaneous values of emf and current are respectively e$=200\sin (\omega t-\frac{\pi }{3});$ i$=10\sin (\omega t+\frac{\pi }{6})$. The phase relation between current and voltage is

• A. Voltage lags behind current by a phase angle of $\frac{\pi }{3}$
• B. Current leads voltage by a phase angle of $\frac{\pi }{6}$
• C. Current leads voltage by a phase angle of $\frac{\pi }{2}$
• D. Voltage leads current by a phase angle of $\frac{\pi }{2}$

Answer 1

Answer: (C)

Current leads voltage by a phase angle of $\frac{\pi }{2}$

The phase of the current $=\omega t+\frac{\pi }{6}$

The phase of voltage $=\omega t-\frac{\pi }{3}$

Hence the current leads voltage by phase angle $(\omega t+\frac{\pi }{6})-(\omega t-\frac{\pi }{3})$ $=\frac{\pi }{2}$