Question

An inductor $L$ with small resistance, a resistor $R$ and two identical bulbs, $B_1$ and $B_2$ are connected to a battery through a switch $S$ as shown in the figure. Which of the following statements gives the correct description of the happenings when the switch $S$ is closed?

• A. The bulb $B_2$ lights up earlier than $B_1$ and finally both the bulbs shine equally bright.
• B. The bulb $B_1$ lights up earlier than $B_2$ and finally both the bulbs shine equally bright.
• C. The bulb $B_2$ lights up earlier than $B_1$ and finally $B_1$ shines brighter than $B_2$.
• D. Both the bulbs, $B_1$ and $B_2$ light up together with equal brightness all the time.

Answer 1

The correct option is C The bulb $B_2$ lights up earlier than $B_1$ and finally $B_1$ shines brighter than $B_2$.


The current in the resistor will rise instantaneously and in the inductor, gradually from zero when switch $S$ is closed.

So, the bulb $B_2$ lights up earlier than $B_1$.

After, the current attains a steady value in the inductor, the bulb $B_1$ will shine brighter than $B_2$ as the resistance of the inductor $L$ is negligibly small.

Hence, option $\left(C\right)$ is the correct answer.