If the current $30 \,A$ flowing in the primary coil is made zero in $0.1 \,s$,the $e.m.f.$ induced in the secondary coil is $1.5 \,V$. The mutual inductance between the coils is.....$H$.

Two concentric coplanar circular conducting loops have radii $R$ and $r$ $(R \gg r)$. Their mutual inductance is proportional to

$A$ coil of radius $1\, cm$ and $100$ turns is placed in the middle of a long solenoid of radius $5\, cm$ having $5\, turns/cm$, with its axis parallel to the axis of the solenoid. The mutual inductance in millihenry is:

The coefficient of mutual inductance between the primary and the secondary coil of a transformer is $0.2 H$. When the current in the primary coil changes at a rate of $5 A s^{-1}$,the induced emf in the secondary coil will be: (in $V$)

Two coils $A$ and $B$ have a coefficient of mutual inductance $M = 2 \ H$. The magnetic flux passing through coil $A$ changes by $4 \ Wb$ in $10 \ s$ due to the change in current in coil $B$. Then:

$A$ varying current at the rate of $3 \, A/s$ in a coil generates an $e.m.f.$ of $8 \, mV$ in a nearby coil. The mutual inductance of the two coils is: