1.

A light bulb is rated at 100W for a 220 V supply. Findthe resistance of the bulb

Answer»

Solution : (a) Rating of given is "100W, 220V". It means that maximum VOLTAGE that can beapplied to a given bulb is 220V and at that voltage maximum POWER consumed by that bulb will be 100W. Now, we have the FORMULAFOR average electrical power,
`P = ( V^(2))/( R )`( Where R = electricalresistance of given bulb)
`:. R = ( V^(2))/( P )`
`:. R = ((220)^(2))/( 100)`
`:. R = 484 Omega`


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