Question

An electric bulb is rated 220 volt and 100 watt. Power consumed by it when operated on 110 volt is

• A. 50 watt
• B. 75 watt
• C. 90 watt
• D. 25 watt

Answer 1

The correct option is D 25 watt

$P=\frac{V^2}{R}$
When $V=220VP=100W$
$P=\frac{(\frac{V}{2}{)}^2}{R}=\frac{V^2}{4R}=25W$