Two coils of self-inductances $2\, mH$ and $8\, mH$ are placed so close together that the effective flux in one coil is completely linked with the other. The mutual inductance between these coils is......$mH$.

There are two coils $A$ and $B$ separated by some distance. If a current of $2 \ A$ flows through $A$,a magnetic flux of $10^{-2} \ Wb$ passes through $B$ (no current through $B$). If no current passes through $A$ and a current of $1 \ A$ passes through $B$,what is the flux through $A$?

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

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

Two coils have a mutual inductance of $0.01 \ H$. The current in the first coil changes according to the equation $I = 5 \sin(200 \pi t)$. The maximum value of the e.m.f. induced in the second coil is:

$A$ small square loop of wire of side $l$ is placed inside a large square loop of wire $L$ $(L \gg l)$. Both loops are coplanar and their centres coincide at point $O$ as shown in the figure. The mutual inductance of the system is: