Two bulbs marked 220 V, 200 W and 220 V, 1000 W, respectively, are connected in series to 220 V mains supply. The ratio of heat generated in them, respectively will be
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 5 : 1 \)
The resistance of a bulb rated \( V \), \( P \) is \( R = V^{2}/P \), so for the same rated voltage \( R \propto 1/P \).
\( \displaystyle R_1 : R_2 = \frac{1}{200} : \frac{1}{1000} = 5 : 1 \)
In series the same current flows through both, so the heat generated \( H = I^{2}Rt \) is proportional to the resistance.
\( \displaystyle \frac{H_1}{H_2} = \frac{R_1}{R_2} = \frac{5}{1} \)