question_answer

Electric bulb 50 W-100 V glowing at full power are 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 \[E=V+ir\] \[\Rightarrow \,\,\,\,\,120=100+\left( \frac{n}{2} \right)\times 10\,\,\,\,\Rightarrow \,\,\,n=4\]