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When three identical bulbs of `60 W, 200 V` rating are connected in series to a `200 V` supply, the power drawn by them will beA. `60 W`B. `180 W`C. `10 W`D. `20 W` |
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Answer» Correct Answer - D (d) Let `R_(1), R_(2)` and `R_(3)` are the resistance of three bulbs respectively. In series order, `R = R_(1) + R_(2) + R_(3)` but `R = V_(2)//P` and supply voltage in series order is the same as the rated voltage. `:. (V^(2))/(P) = (V^(2))/(P_(1)) + (V^(2))/(P_(2)) + (V^(2))/(P_(3))` or `(1)/(P) = (1)/(60) + (1)/(60) + (1)/(60)` or `P = (60)/(3) = W` |
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