If a change in current of $0.01\, A$ in one coil produces a change in magnetic flux of $1.2 \times 10^{-2}\,Wb$ in the other coil,then the mutual inductance of the two coils in henries is.....$H$

$A$ small square loop of wire of side $l$ is placed inside a large square loop of side $L$ $(L \gg l)$. If the loops are coplanar and their centres coincide,the mutual inductance of the system is directly proportional to :

Two coils having self-inductance $L_1 = 75 \text{ mH}$ and $L_2 = 48 \text{ mH}$ are coupled with each other. If the mutual inductance of the coils is $37.2 \text{ mH}$, then the coefficient of coupling will be:

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

Consider a conducting wire of length $L$ bent in the form of a circle of radius $R$ and another conductor of length $a$ $(a \ll R)$ is bent in the form of a square. The two loops are then placed in the same plane such that the square loop is exactly at the centre of the circular loop. What will be the mutual inductance between the two loops?

$A$ coil of radius $r$ is placed on another coil (whose radius is $R$ and current flowing through it is changing) so that their centres coincide. $(R \gg r)$ If both the coils are coplanar,then the mutual inductance between them is proportional to