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
Given:
Bulb A: 220 V, 200 W Bulb B: 220 V, 1000 W
First, calculate the resistance of each bulb using the formula:
$R = \frac{V^2}{P}$
For Bulb A:
$R_1 = \frac{220^2}{200} = \frac{48400}{200} = 242\,\Omega$
For Bulb B:
$R_2 = \frac{220^2}{1000} = \frac{48400}{1000} = 48.4\,\Omega$
Since they are connected in series, the same current flows through both. Heat produced in time $t$ is given by:
$H = I^2 R t$
So, the ratio of heat generated is proportional to their resistances:
$\frac{H_1}{H_2} = \frac{R_1}{R_2} = \frac{242}{48.4} = 5:1$