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? |
Both 100 W 25 W Neither |
25 W |
$ 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$ $\text{ 25W bulb will fuse first}$ |