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26/09/2021 5:55 pm
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An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be
(a) 100 W
(b) 75 W
(c) 50 W
(d) 25 W
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26/09/2021 5:58 pm
Correct answer: (d) 25 W
Explanation:
As per the equation P = V2/R
we have If V = 220 V
100 W = 2202/R
R = 2202/100 Ω = 484 Ω.
This is the resistance of the bulb.
When V = 110 V, power consumed = V2/R
= 1102/484 = 25 W.
So, 25 W power is consumed when it is operated on 110 V.