# An electric bulb is rated $220V$- $100W$. The power consumed by it when it operates on $110V$ is

$\begin {array} {1 1} (A)\;50W & \quad (B)\;25W \\ (C)\;100W & \quad (D)\;400W \end {array}$

$\large\frac{V^2_1}{P_1}$ $\large\frac{V^2_2}{P_2}$ = Resistance
$\Rightarrow P_2 = 25W$
Ans : (B)
edited Mar 14, 2014