An electric bulb is rated 220V and 100W
Power consumed when it is operated on 110 V
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.