Question

The variation of the instantaneous current (I) and the instantaneous emf(E) in a circuit is as shown in figure. Which of the following statements is correct?

• A. The voltage lags behind the current by $\pi /2$
• B. The voltage leads the current by $\pi /2$
• C. The voltage and the current are in phase
• D. The voltage leads the current by $\pi$

Answer 1

Answer: (B)

The voltage leads the current by $\pi /2$

Here voltage $V=E\sin \omega t$

and current $i=I\sin (\omega t-\frac{\pi }{2})$, since

at t = 0 , V=E and i = -I

Hence voltage V, leads the current by $\frac{\pi }{2}$