Two circular coils can be arranged in any of the three situations shown in the figure. Their mutual inductance will be

Two concentric circular coils having radii $r_{1}$ and $r_{2}$ $(r_{2} \ll r_{1})$ are placed coaxially with centers coinciding. The mutual inductance of the arrangement is (Both coils have a single turn) ($\mu_{0} =$ permeability of free space).

Write the formula for the mutual inductance of two very long coaxial solenoids of length $l$.

$A$ small square loop of wire of side $l$ is placed inside a large circular loop of radius $r$. The loops are coplanar and their centers coincide. The mutual inductance of the system is proportional to

Two coils $P$ and $Q$ are kept near each other. When no current flows through coil $P$ and current increases in coil $Q$ at the rate $10 \ A/s$,the emf in coil $P$ is $12 \ mV$. When coil $Q$ carries no current and current of $1.5 \ A$ flows through coil $P$,the magnetic flux linked with the coil $Q$ in $mWb$ is

Two coils have a mutual inductance $0.005 \, H$. The current changes in the first coil according to the equation $I = I_0 \sin(\omega t)$,where $I_0 = 10 \, A$ and $\omega = 100\pi \, rad/s$. The maximum value of the $e.m.f.$ in the second coil is: