Question

An electric bulb is rated $220V$ and $100W$ . When it is operated om $110V$,the power consumed will be-

• A. $100W$
• B. $75W$
• C. $50W$
• D. $25W$

Answer 1

The correct option is D $25W$

Given,

$P_1=100W$

$V_1=220V$

$P_2=?$

$V_2=110V$

Power, $P=\frac{V^2}{R}$

$\frac{P_2}{P_1}=(\frac{V_2}{V_1}{)}^2$

$\frac{P_2}{P_1}=(\frac{110}{220}{)}^2=\frac{1}{4}$

$P_2=\frac{P_1}{4}=\frac{100}{4}$

$P_2=25W$

The correct option is D.