$A$ small square loop of wire of side $\ell$ is placed inside a large square loop of wire of side $L$ $(L \gg \ell)$. The loops are coplanar and their centers coincide. The value of the mutual inductance of the system is $\sqrt{x} \times 10^{-7} \text{ H}$, where $x = \dots$

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 $\,H$)

$A$ circular loop of radius $0.3 \ cm$ lies parallel to a much bigger circular loop of radius $20 \ cm$. The centre of the smaller loop is on the axis of the bigger loop. The distance between their centres is $15 \ cm$. If a current of $2.0 \ A$ flows through the smaller loop,then the flux linked with the bigger loop is $............. \times 10^{-11} \ Wb$.

Two coils $A$ and $B$ are placed in a circuit. When current in the coil $A$ changes by $0.8 \,A$, the magnetic flux in coil $B$ changes by $0.16 \,Wb$. The mutual inductance between the coils is (in $\,H$)

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

Alternating current of peak value $(\frac{2}{\pi}) \ A$ flows through the primary coil of a transformer. The coefficient of mutual inductance between the primary and secondary coil is $1 \ H$. The peak e.m.f. induced in the secondary coil is (Frequency of a.c. $= 50 \ Hz$) (in $V$)