Question

When electric bulbs of same power, but different marked voltage are connected in series across the power line, their brightness will be :
A. proportional to their marked voltage
B. inversely proportional to their marked voltage
C. porportional to the square of their marked voltage
D. inversely porportional to the square of their marked voltage

Answer 1

Correct Answer - C
(c ) Resistance of bulb `R = (V^(2))/(P)` , Where `V` is the marked voltage and `P` is the marked power `P`.is same for both As both bulbs are connceted in series, so current in both of them will be same. So Brightness `prop R prop V^(2)`