Question

An inductance $L$ and a resistance $R$ are first connected to a battery. After attaining steady state, the battery is disconnected but $L$ and $R$ remain connected in a closed circuit. Then, the current reduces to $37\%$ of its initial value in time -

• A. $RL$
• B. $\frac{R}{L}$
• C. $\frac{L}{R}$
• D. $\frac{1}{LR}$

Answer 1

The correct option is C $\frac{L}{R}$

The time taken by the current to decay from $i_0$ to $37\%$ of $i_0$ is equal to the time constant given by,

$\tau =\frac{L}{R}$

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