Q.
If $R_{1}\ and\ R_{2}$ be the resistances of the filaments of 200 W and 100 W electric bulbs operation at 220 V, then $\left( \frac{R_{1}}{R_{2}} \right)$ is
A) 1
B) 2
C) 0.5
D) 4
Explanation
(c) Power of bulb, $P = \frac{V^{2}}{R}$
$\therefore\ \frac{P_{2}}{P_{1}} = \frac{R_{1}}{R_{2}}$
Or $\frac{R_{1}}{R_{2}} = \frac{100}{200} = 0.5$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.