Q. A 200 W and a 100 W bulb, both meant for operation at 220 V are connected in series. When connected to a 220 V supply the power consumed by the combination is
A) 33.3 W
B) 66.7 W
C) 300 W
D) 100 W
Explanation
(b) When two similar bulbs of different powers are connected in series, then
$\frac{1}{P} = \frac{1}{P_{1}} + \frac{1}{P_{2}}$
Given, $P_{1} = 200\ W,\ P_{2} = 100\ W$
$\Rightarrow \frac{1}{P} = \frac{1 + 2}{200}$
$\Rightarrow P = \frac{200}{3} = 66.7\ W$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.