$A$ coil of resistance $400\,\Omega$ is placed in a magnetic field. If the magnetic flux $\phi$ (in $Wb$) linked with the coil varies with time $t$ (in $s$) as $\phi = 50t^2 + 4$,the current in the coil at $t = 2\,s$ is $..........\,A$.

The induced emf cannot be produced by:

Discuss Faraday's experiment of two coils for the generation of electric current in a coil.

Three identical coils $C_1, C_2$ and $C_3$ are placed coaxially. $C_2$ is exactly midway between $C_1$ and $C_3$. $C_1$ carries current $I$ in an anti-clockwise direction, while $C_3$ carries current $I$ in a clockwise direction. An induced current flows through $C_2$ in a clockwise direction when:

$A$ coil of effective area $3 \text{ m}^2$ is placed at right angles to a magnetic field of induction $0.05 \text{ Wb/m}^2$. If the field is decreased to $20\%$ of its original value in $10 \text{ seconds}$, the e.m.f. induced in the coil will be (in $\text{ mV}$)

In the given figure,the magnet is moved towards the coil with speed $v$ and the induced $emf$ is $e$. If the magnet and the coil recede away from one another,each moving with speed $v$,the induced $emf$ in the coil will be