# Give the expression for average value of a.c voltage $V = V_0\; sin \omega t$ over time interval $t = 0 \; to \; t = \frac {\pi}{\omega}$
(a) $\frac {2V_0}{\pi}$
(b) $\frac {V_0}{2\pi}$
(c) $\frac {V_0}{\pi}$
(d) $\frac {\pi V_0}{2}$