An electric bulb, when connected across a power supply of 220 W, consumes a power of 60 W. If the supply drops to 180 V, what will be the power consumed? If the supply is suddenly increased to 240 V, what will be the power consumed?

Question

Philoid · Accepted Answer

If P is the power consumed by the bulb when operated at voltage V, then by Joule’s heating effect-

Now when the supply drops to V’ = 180 V

The power consumed,

(b) Now the supply changes to, V” = 240 V.

Therefore,