$A$ graph of magnetic flux $(\phi)$ versus current $(I)$ is plotted for four inductors $A, B, C, D$. Which inductor has the largest value of self-inductance?

When a current in the conducting coil is changed from $5 \ A$ in one direction to $5 \ A$ in the opposite direction in $0.5 \ s$,an average induced e.m.f. in the coil is $2 \ V$. The self-inductance of the coil is (in $mH$)

$A$ long coaxial cable carries current $I$ along its surface. The current flows down the surface of the inner cylinder of radius $a$ and back along the outer cylinder of radius $b$.

When the number of turns in a coil is doubled without any change in the length of the coil,its self-inductance

An $e.m.f.$ of $12$ $V$ is induced in a coil when the current in it changes at the rate of $48$ $A/min$. The self-inductance of the coil is:

In an induction coil with resistance,the induced emf will be maximum when