An $e.m.f.$ of $100$ $millivolts$ is induced in a coil when the current in another nearby coil becomes $10$ $ampere$ from zero in $0.1$ $second.$ The coefficient of mutual induction between the two coils will be....$millihenry$

Two circuits have mutual inductance of $0.1\, H$. What average $e.m.f$. is induced in one circuit when the current in the other circuit changes from $0$ to $20\, A$ in $0.02$ $s$......$V$

Write formula for mutual inductance for two very long coaxial solenoids of length $\mathrm{l}$.

The induction coil works on the principle of

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

A coil of radius $1\, cm$ and of turns $100$ is placed in the middle of a long solenoid of  radius $5\, cm$. and having $5\, turns/cm$. parallel to the axis of solenoid The mutual  inductance in millihenery will be