A small circular loop of wire of radius $a$ is located at the centre of a much larger circular wire loop of radius $b$. The two loops are in the same plane. The outer loop of radius $b$ carries an alternating current $I = I_0\, cos\, (\omega t)$ . The emf induced in the smaller inner loop is nearly
$\frac{{\pi {\mu _0}{I_0}}}{2}.\frac{{{a^2}}}{b}\omega \,\sin \,\left( {\omega t} \right)$
$\frac{{\pi {\mu _0}{I_0}}}{2}.\frac{{{a^2}}}{b}\omega \,\cos \,\left( {\omega t} \right)$
$\pi {\mu _0}{I_0}\,\frac{{{a^2}}}{b}\omega \,\sin \,\left( {\omega t} \right)$
$\frac{{\pi {\mu _0}{I_0}{b^2}}}{a}\,\omega \,\cos \,\left( {\omega t} \right)$
Two circular coils have their centres at the same point. The mutual inductance between them will be maximum when their axes
Two coils of self inductance ${L_1}$ and ${L_2}$ are placed closer to each other so that total flux in one coil is completely linked with other. If $M$ is mutual inductance between them, then $M$ is
The mutual inductance of an induction coil is $5\,H$. In the primary coil, the current reduces from $5\,A$ to zero in ${10^{ - 3}}\,s$. What is the induced emf in the secondary coil......$V$
In a $dc$ motor, induced $e.m.f.$ will be maximum
A short solenoid (length $l$ and radius $r$ with $n$ turns per unit length) lies well inside and on the axis of a very long, coaxial solenoid (length $L$, radius $R$ and $N$ turns per unit length, with $R>r$ ). Current $I$ follows in the short solenoid. Choose the correct statement.