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 $\,H$)

The planar concentric rings of metal wire having radii $r_1$ and $r_2$ (with $r_1 > r_2$) are placed in air. The current $I$ is flowing through the coil of larger radius. The mutual inductance between the coils is given by $(\mu_0 = \text{permeability of free space})$

Two circular coils have their centers at the same point. The mutual inductance between them will be maximum when their axes

$O$ is the centre of two coplanar concentric circular conductors,$A$ and $B$,of radii $r$ and $R$ respectively as shown in the figure. Here $r \ll R$. The mutual inductance of the system of the conductors can be given by . . . . . . .

Two coils $A$ and $B$ have mutual inductance $0.008 \ H$. The current changes in the coil $A$, according to the equation $I = I_{m} \sin \omega t$, where $I_{m} = 5 \ A$ and $\omega = 200 \pi \ rad \ s^{-1}$. The maximum value of the e.m.f. induced in the coil $B$ in volt is (in $\pi$)

Two coils $A$ and $B$ are wound on the same iron core as shown in the figure. The number of turns in the coils $A$ and $B$ are $N_A$ and $N_B$ respectively. Identify the correct statement.