Question

Two electric bulbs marked 25W – 220V and 100W – 220V are connected in series to a 440Vsupply. Which of the bulbs will fuse? A) 25 W B) Both C) 100 W D) Neither

Answer 1

Answer:

A) 25 W

Explanation:

Resistances of both the bulbs are

 

R1=V^2/P1 = 220^2/25

 

R2 = V^2/P2 = 220^2/100

 

Hence  R1gt ; R2

 

When connected in series, the voltages divide in them in the ratio of their resistances. The voltage of 440 V devides in such a way that voltage across 25 w bulb will be more than 220 V. Hence 25 w bulb will fuse