The energy stored in a $50 mH$ inductor carrying a current of $4 A$ is (in $J$)

When a current $I$ flows through a coil,it stores the energy $E_1$ in it. Now the current is reduced to $I/2$,the energy stored in the coil becomes $E_2$. The change in the energy is

Energy required to establish a current of $4 \ A$ in a coil of self-inductance $L = 200 \ mH$ is . . . . . . . (in $J$)

If a current flowing in a coil is reduced to half of its initial value,the relation between the new energy $(E_2)$ and the original energy $(E_1)$ stored in the coil will be

$A$ coil of self-inductance $0.5 \ mH$ carries a current of $2 \ A$. The energy stored in Joule is . . . . . . .

The magnetic potential energy stored in a certain inductor is $25\, mJ,$ when the current in the inductor is $60\, mA.$ This inductor is of inductance ......$H$.