If bulb rating is 100 walt and 220 V then determine
(a) Resistance of filament
(b) Current through filament
(c ) If bulb operate at 110 volt power supply then find consumed by bulb.

Explanation

Bulb rating in 100 W and 200 V bulb means when 220 V potential difference is applied between the two ends then power consume is 100 W
Here `V=220`
`P=100`
`(V^(2))/(R)=100`
So `R=484Omega`
Since Resistance depends only on material hence it is constant for bulb
`I=(V)/(R)=(220)/(22xx22)=(5)/(11)`Amp.
power consumed at 110 V
`therefore` power consumed `=(110xx110)/(484)=25W`