In $SI$, Henry is the unit of

A small square loop of wire of side $l$ is placed inside a large circular loops of radius $r$. The loop are coplanar and their centre coincide. The mutual inductance of the system is proportional to

The mutual inductance between two coils is $1.25$ $henry$. If the current in the primary changes at the rate of $80$ $ampere/second,$ then the induced $e.m.f$ in the secondary is......$V$

A small square loop of wire of side $\ell$ is placed inside a large square loop of wire of side $L$ $\left(\mathrm{L}=\ell^2\right)$. The loops are coplanar and therr centers coinside. The value of the mutual inductance of the system is $\sqrt{\mathrm{x}} \times 10^{-7} \mathrm{H}$, where X =___

The mutual inductance of a pair of coils, each of $N\,turns$, is $M\,henry$. If a current of $I\, ampere$ in one of the coils is brought to zero in $t$ $second$ , the $emf$ induced per turn in the other coil, in volt, will be

A circular loop of radius $0.3\, cm$ lies parallel to a much bigger circular loop of radius $20 \,cm$. The centre of the small loop on the axis of the bigger loop. The distance between their centres is $15\, cm$. If a current of $20\, A$ flows through the smaller loop, then the flux linked with bigger loop is