The emf induced in the secondary coil due to unit rate of change of current in the primary is called

There are $10$ turns in coil $M$ and $15$ turns in coil $N$. If a current of $2\ A$ is passed through coil $M$,then the flux linked with coil $N$ is $1.8 \times 10^{-3}\ Wb$. If a current of $3\ A$ is passed through coil $N$,then the flux linked with coil $M$ is:

Two circuits have a 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 $0.02\, s$ (in $, V$)?

$A$ pair of adjacent coils has a mutual inductance of $1.5 \ H$. If the current in one coil changes from $0$ to $20 \ A$ in $0.5 \ s$,what is the change of flux linkage with the other coil (in $Wb$)?

$A$ coil of radius $r$ is placed on another coil (whose radius is $R$ and current flowing through it is changing) so that their centres coincide. $(R \gg r)$ If both the coils are coplanar,then the mutual inductance between them is proportional to

$A$ transformer works on the principle of