The mutual inductance of a system of two coils does not depend on . . . . . . .

If the coefficient of mutual induction of the primary and secondary coils of an induction coil is $5\, H$ and a current of $10\, A$ is cut off in $5\times10^{-4}\, s$,the $emf$ induced (in $volt$) in the secondary coil is

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

An electric current $i_1$ can flow in either direction through loop $(1)$ and induces a current $i_2$ in loop $(2)$. Positive $i_1$ is defined when the current flows from $'a'$ to $'b'$ in loop $(1)$,and positive $i_2$ is defined when the current flows from $'c'$ to $'d'$ in loop $(2)$. In an experiment,the graph of $i_2$ against time $'t'$ is as shown below. Which one$(s)$ of the following graphs could have caused $i_2$ to behave as given above?

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 $\pi$)

$A$ small square loop of wire of side $l$ is placed inside a large square loop of side $L$ $(L \gg l)$. If the loops are coplanar and their centres coincide,the mutual inductance of the system is directly proportional to :