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

Explanation

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