The current in a coil of inductance $0.2 \,H$ changes from $5 \,A$ to $2 \,A$ in $0.5 \,s$. The magnitude of the average induced emf in the coil is (in $\,V$)

Consider a toroid with a rectangular cross-section,of inner radius $a$,outer radius $b$,and height $h$,carrying $n$ number of turns. Then the self-inductance of the toroidal coil when current $I$ is passing through the toroid is:

$A$ coil is wound as a transformer of rectangular cross-section. If all the linear dimensions of the transformer are increased by a factor of $2$ and the number of turns per unit length of the coil remains the same,the self-inductance increases by a factor of:

$A$ choke coil works on the principle of

Define inductance, give its units and write factors on which its value depends.

$A$ 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 ...... $mH$.