The area of a coil is $A$. The coil is placed in a magnetic field which changes from $B_{0}$ to $4 B_{0}$ in time $t$. The magnitude of the induced e.m.f. in the coil will be:

The magnetic flux through a coil is $4 \times 10^{-4} \ Wb$ at time $t=0$. It reduces to $30 \%$ of its original value in time $t$ seconds. If the e.m.f. induced in the coil is $0.56 \ mV$,then the value of $t$ is: (in $s$)

An insulated copper wire of $100$ turns is wrapped around a wooden cylindrical core of the cross-sectional area $24\,cm^2$. The two ends of the wire are connected to a resistor. The total resistance in the circuit is $12\,\Omega$. If an externally applied uniform magnetic field in the core along its axis changes from $1.5\,T$ in one direction to $1.5\,T$ in the opposite direction,the charge flowing through a point in the circuit during the change of magnetic field will be $.........\,mC$.

When the switch is closed in the primary circuit,the instantaneous induced current in the secondary circuit is:

$A$ bar magnet is allowed to fall vertically through a copper coil placed in a horizontal plane. The magnet falls with a net acceleration:

In electromagnetic induction,the induced $e.m.f.$ in a coil is independent of