Two electric bulbs marked 25 W-220 V and 100 W-220 V are connected in series to a 440 V supply. Which of the bulbs will fuse?
Answer & explanation
Correct answer: option 3
$ R = \frac{V^2}{P} $
$ R_1 = \frac{220^2}{25}= 1936\Omega , R_2 = \frac{220^2}{100} = 484\Omega$
$ R_{eq} = R_1 + R_2 = 2420$
$ I = \frac{440}{2420} = 0.18A$
$ P_1 = I^2R_1=62.72W , P_2 = I^2R_2 = 15.68W$
$\text{ 25W bulb will fuse first}$