Question

An electric bulb is rated $220V$ and $100W$, when it is operated on $110V$, the power consumed will be

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

Answer 1

Answer: (D)

D. $25W$

Formulae,

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

$\Rightarrow R=\frac{V^2}{P}$

$=\frac{{220}^2}{100}=484\Omega$

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

$P=\frac{{110}^2}{484}=25W$