Q. If two electric bulbs have $40\ W$ and $60\ W$ rating at $220\ V,$ then the ratio of their resistances will be
A) 9 :4
B) 4 :3
C) 3 :8
D) 3 :2
Explanation
(d) $P_{Rated} \propto \frac{1}{R} \Rightarrow \frac{R_{1}}{R_{2}} = \frac{P_{2}}{P_{1}} = \frac{60}{40} = \frac{3}{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.