In a circular conducting coil,when current increases from $2 \,A$ to $18 \,A$ in $0.05 \,s$,the induced $e.m.f.$ is $20 \,V$. The self-inductance of the coil is.....$mH$.

The average $e.m.f.$ induced in a coil in which the current changes from $2 \ A$ to $4 \ A$ in $0.05 \ s$ is $8 \ V.$ What is the self-inductance of the coil in $H$?

In a fluorescent lamp choke (a small transformer),$100 \; V$ of reverse voltage is produced when the choke current changes uniformly from $0.25 \; A$ to $0 \; A$ in a duration of $0.025 \; ms$. The self-inductance of the choke (in $mH$) is estimated to be:

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.....$\%$

$A$ coil of $N = 100$ turns carries a current $I = 5 \, A$ and creates a magnetic flux $\phi = 10^{-5} \, Wb$ per turn. The value of its inductance $L$ will be ...... $mH$.

Physically,the self-inductance plays the role of