$A$ current $2 \ A$ flows through a solenoid of self-inductance $3 \ mH$. The energy stored inside the solenoid is $.... \ mJ$.

$A$ solenoid of inductance $2 \ H$ carries a current of $1 \ A$. What is the magnetic energy stored in the solenoid (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

The magnetic energy stored in an inductor of inductance $4\,\mu H$ carrying a current of $2\,A$ is:

Assertion : If the current in a solenoid is reversed in direction while keeping the same magnitude,the magnetic field energy stored in the solenoid remains unchanged.
Reason : Magnetic field energy density is proportional to the magnetic field.

$(a)$ Obtain the expression for the magnetic energy stored in a solenoid in terms of magnetic field $B$,area $A$,and length $l$ of the solenoid.
$(b)$ How does this magnetic energy compare with the electrostatic energy stored in a capacitor?