question_answer

Electric bulb 50 W-100 V glowing at full power is  to be used in parallel with battery 120 V, \[10\Omega .\]Maximum number of bulbs that can be connected so that they glow in full power is

A)  2

B)  8

C)  4

D)  6

Correct Answer: C

Solution :

When each bulb is glowing at full power, Current from each bulb \[=i'=\frac{50}{100}=\frac{1}{2}A\] So main current \[i=\frac{n}{2}A\] Also \[E=V+ir\Rightarrow 120=100+\left( \frac{n}{2} \right)\times 10\Rightarrow n=4\]