The current through a choke coil increases from zero to $6 \ A$ in $0.3 \ s$ and an induced $e.m.f.$ of $30 \ V$ is produced. The inductance of the choke coil is ....... $H$.

$A$ graph of magnetic flux $(\phi)$ versus current $(I)$ is plotted for four inductors $A, B, C, D$. Which inductor has the largest value of self-inductance?

In the following circuit,the bulb will become suddenly bright if

The self-inductance of a coil is $50 mH$. When a current of $1 A$ passing through the coil reduces to zero at a steady rate in $0.1 s$,find the self-induced emf. (in $V$)

$A$ coil is wound on a core of rectangular cross-section. If all the linear dimensions of the core are increased by a factor of $2$ and the number of turns per unit length of the coil remains the same, the self-inductance increases by a factor of (Assume, permeability is same).

Two different coils have self-inductance $3L$ and $L$. The current in both the coils is increased at the same constant rate. At a certain instant of time, the power given to the two coils is same. At that time, there was current and voltage induced in the two coils. At the same instant, the ratio of energy stored in the first coil to that in the second coil is