Two concentric circular coils,one of small radius $r_1$ and the other of large radius $r_2$,such that $r_1 \ll r_2$,are placed co-axially with their centres coinciding. The mutual inductance $M$ of the arrangement is proportional to . . . . . . .

$A$ primary coil and a secondary coil are placed close to each other. $A$ current, which changes at the rate of $25 \, A$ in a millisecond, is present in the primary coil. If the mutual inductance is $92 \times 10^{-6} \, H$, then the value of the induced emf in the secondary coil is:

Two different coils of self-inductance $L_{1}$ and $L_{2}$ are placed close to each other so that the effective flux in one coil is completely linked with the other. If $M$ is the mutual inductance between them,then:

Two coaxial coils are very close to each other and their mutual inductance is $5 \,mH$. If a current $i = 50 \sin(500t) \,A$ is passed in one of the coils,then the peak value of the induced e.m.f. in the secondary coil will be ........... $V$.

Two concentric circular coils,one of small radius $r_1$ and the other of large radius $r_2$,such that $r_1 \ll r_2$,are placed coaxially with centers coinciding. Obtain the mutual inductance of the arrangement.

An alternating current of angular frequency $\omega = 200 \, rad/sec$ and peak value $I_0 = 1 \, A$,as shown in the figure,is applied to the primary coil of a transformer. If the coefficient of mutual induction between the primary and the secondary coil is $M = 1.5 \, H$,the magnitude of the induced voltage in the secondary coil will be.....$V$.