Two coils have a mutual inductance $0.005 \, H$. The current changes in the first coil according to the equation $I = I_0 \sin(\omega t)$,where $I_0 = 10 \, A$ and $\omega = 100\pi \, rad/s$. The maximum value of the $e.m.f.$ in the second coil is:

An alternating current with an angular frequency of $\omega = 200\,rad/s$ and a peak value of $I_0 = 1\,A$,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 coils is $M = 1.5\,H$,the magnitude of the induced voltage in the secondary coil will be.....$V$.

$A$ long straight wire is placed along the axis of a circular ring of radius $R$. The mutual inductance of this system is

Two concentric circular coils having radii $r_1$ and $r_2$ $(r_2 \ll r_1)$ are placed co-axially with centres coinciding. The mutual inductance of the arrangement is (Both coils have single turn, $\mu_0$ = permeability of free space)

Two concentric circular coils having radii $r_1$ and $r_2$ $(r_2 \ll r_1)$ are placed co-axially with centres coinciding. The mutual induction of the arrangement is (Both coils have single turn,$\mu_0 =$ permeability of free space).

The coefficient of mutual induction is $3 \text{ H}$ and induced e.m.f. across secondary is $4 \text{ kV}$. Current in primary is reduced from $7 \text{ A}$ to $2 \text{ A}$. The time required for the change of current is