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A 220 volt, 1000 watt bulb is connected across a 110 volt mains supply. The power consumed will be

Asked in JEE Main 2003 · Rated bulbs and appliances

(1) 750 watt
(2) 500 watt
(3) 250 watt
(4) 1000 watt

Answer: (3) 250 watt

Step-by-step solution

Resistance: R=(220²)/(1000)=48.4 Ω, unchanged.

P=(V²)/R=(110²)/(48.4).

P=250 W, one quarter of the rated value.

Why the other options are wrong

(1) No standard slip gives this; it would need the power to fall by only a quarter.
(2) Takes power proportional to V instead of V².
(4) Assumes the bulb always draws its rated power, whatever the supply voltage.

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