The voltage and current in an a.c. circuit are given by \( V = 8\sin\left(50\pi t - \displaystyle\frac{\pi}{3}\right) \) volt and \( I = 6\sin\left(50\pi t + \displaystyle\frac{\pi}{3}\right) \) A. The correct phase relationship between voltage and current is
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Current leads the voltage by \( 120^\circ \)
Compare the phase angles of the two sinusoids. The one with the larger phase angle reaches its peak earlier, so it leads.
\( \phi_V = -\pi/3 = -60^\circ \)
\( \phi_I = +\pi/3 = +60^\circ \)
\( \phi_I - \phi_V = 60^\circ - (-60^\circ) = 120^\circ \)
So the current leads the voltage by \( 120^\circ \).