Two coils of self-inductance ${L_1}$ and ${L_2}$ are placed close to each other so that the total flux in one coil is completely linked with the other. If $M$ is the mutual inductance between them,then $M$ is:

The mutual inductance $(M)$ of two coils is $3 \ H$. The self-inductances of the coils are $4 \ H$ and $9 \ H$ respectively. The coefficient of coupling between the coils is

Two circular coils of radii $r_1$ and $r_2$ $(r_1 \ll r_2)$ are placed coaxially with their centers coinciding. The mutual inductance of the arrangement is

$A$ square loop of side length $a$ is moving away from an infinitely long current-carrying conductor at a constant speed $v$ as shown. Let $x$ be the instantaneous distance between the long conductor and side $AB$. The mutual inductance $M$ of the square loop-long conductor pair changes with time $t$ according to which of the following graphs?

Two coils $X$ and $Y$ are placed in a circuit such that when a current changes by $2 \ A$ in coil $X$,the magnetic flux changes by $0.4 \ Wb$ in coil $Y$. The value of mutual inductance of the coils is .... $H$.

In a pair of adjacent coils,if the current in one coil changes from $10 \,A$ to $2 \,A$ in a time $0.2 \,s$,an emf of $120 \,V$ is induced in the other coil. The mutual inductance of the pair of coils is: (in $\,H$)