1.

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

Answer»

100W
75W
50W
25W

Solution :As RATING of BULB is 220V, 100W hence `P=VI=V^2/R`
`THEREFORE` Resistance of bulb filament `R=V^2/P=(220 times 220)/100=484 Omega`
When the bulb is operated at a voltage V.=110 V, the POWER consumed is
`P=V^2/R=(110 times 110)/484=25W.]`


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