$A$ varying current in a coil changes from $10 \,A$ to zero in $1.5 \,s$. If the average emf induced in the coil is $200 \,V$, the self-inductance of the coil is (in $\,H$)

$A$ $10 \; \Omega, 20 \; mH$ coil carrying constant current is connected to a battery of $20 \; V$ through a switch. When the switch is opened, the current becomes zero in $100 \; \mu s$. The average emf induced in the coil is $\dots \; V$.

For a solenoid,keeping the turn density constant,if its length is halved and its cross-sectional radius is doubled,then the inductance of the solenoid increases by.....$\%$

The back $e.m.f.$ induced in a coil,when current changes from $1 \ A$ to $0 \ A$ in $1 \ ms$,is $4 \ V$. The self-inductance of the coil is:

Regarding self-inductance:
$A:$ The self-inductance of the coil depends on its geometry.
$B:$ Self-inductance does not depend on the permeability of the medium.
$C:$ Self-induced e.m.f. opposes any change in the current in a circuit.
$D:$ Self-inductance is the electromagnetic analogue of mass in mechanics.
$E:$ Work needs to be done against self-induced e.m.f. in establishing the current.
Choose the correct answer from the options given below:

When the current in a coil changes from $8 \ A$ to $2 \ A$ in $3 \times 10^{-3} \ s$,the induced $e.m.f.$ in the coil is $2 \ V$. The self-inductance of the coil in millihenry $(mH)$ is: