When the current through an inductor is changed from $2 \,A$ to $6 \,A$ in time $2 \,s$, the emf induced in it is $3 \,V$. Then the inductance of the inductor is (in $\,H$)

The self-induced $e.m.f.$ in a $0.1 \, H$ coil when the current in it is changing at the rate of $200 \, A/s$ is......$V$

In a coil of self-inductance $0.5 \, H$,the current varies at a constant rate from $0 \, A$ to $10 \, A$ in $2 \, s$. The $e.m.f.$ generated in the coil is ... $V$.

$A$ current of $0.5 \ A$ is passed through the winding of a long solenoid having $400$ turns. The magnetic flux linked with each turn is $3 \times 10^{-3} \ Wb$. The self-inductance of the solenoid is: (in $H$)

The momentum in mechanics is expressed as $m \times v$. The analogous expression in electricity is

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.....$\%$