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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

Asked in CBSE AIPMT 2004 · Rated bulbs and appliances

(1) 60 watt
(2) 180 watt
(3) 10 watt
(4) 20 watt

Answer: (4) 20 watt

Step-by-step solution

Each bulb: R=(200²)/(60).

Three in series: 3R.

P=(200²)/(3R)=(60)/3=20 W.

Why the other options are wrong

(1) Keeps the power of one bulb on the full supply; putting three in series triples the resistance.
(2) Adds the three rated powers, as if each bulb still had its full 200 V.
(3) No single slip gives this value; 10 W would need six bulbs' resistance in series, not three.

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