$A$ solenoid has $2000$ turns wound over a length of $0.3\,m$. The area of cross-section is $1.2\times10^{-3}\,m^2$. Around its central section,a coil of $300$ turns is closely wound. If an initial current of $1\,A$ is reversed in $0.25\,s$,find the emf induced in the coil in $mV$.

Two coils are kept near each other. When no current passes through the first coil and the current in the $2^{nd}$ coil increases at the rate of $10 \,A/s$, the e.m.f. in the $1^{st}$ coil is $20 \,mV$. When no current passes through the $2^{nd}$ coil and $3.6 \,A$ current passes through the $1^{st}$ coil, the flux linkage in coil $2$ is:

Two coils have a mutual inductance of $0.005 \text{ H}$. The current changes in the first coil according to equation $I = I_0 \sin \omega t$, where $I_0 = 10 \text{ A}$ and $\omega = 60\pi \text{ rad s}^{-1}$. The maximum value of e.m.f. in the second coil in volt will be (in $\pi$)

Derive the formula for mutual inductance of two very long coaxial solenoids. Also,discuss the reciprocity theorem.

$A$ solenoid has $2000$ turns wound over a length of $0.30 \ m$. The area of its cross-section is $1.2 \times 10^{-3} \ m^2$. Around its central section,a coil of $300$ turns is wound. If an initial current of $2 \ A$ in the solenoid is reversed in $0.25 \ s$,the emf induced in the coil is equal to

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