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An electric bulb is rated 220V and 100W....

An electric bulb is rated 220V and 100W. When it is operated on 110V the power consumed will be …………… .

A

100W

B

75W

C

50W

D

25W

Text Solution

Verified by Experts

The correct Answer is:
D
Here, the power rating of the electric bulb is P = 100W and the voltage rating is V = 220V
So, the resistance of the filament of the bulb is
`R = V^2/P`
`=((220)^2)/100`
`=484 Omega`

Now, the power consumed by the bulb when it is operated at 110 V is given by
`P. +(V.^2)/(R)`
` =((110)^2)/(484) = (110xx110)/484 =25 W`
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