When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be:
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Question

When three identical bulbs of 60 watt, 200 volt rating are connected in series to a 200 volt supply, the power drawn by them will be:

G1 Physics · Accepted Answer

Step 1: Each bulb has resistance R = V²/P = 200²/60. Step 2: Three identical bulbs in series have Rₜₒₜ = 3R. Step 3: Total P = 200²/(3R) = (1/3)×60 = 20 W.