If the flux associated with a coil of $60$ turns varies at the rate of $1 \text{ Wb/hour}$,the induced emf is . . . . . . .

Magnetic flux $\phi$ (in weber) linked with a closed circuit of resistance $10\, \Omega$ varies with time $t$ (in seconds) as $\phi = 5t^2 - 4t + 1$. The induced electromotive force in the circuit at $t = 0.2\, s$ is ......... $V$.

Consider a metal ring kept on top of a fixed solenoid (say on a cardboard) as per the figure. The center of the ring coincides with the axis of the solenoid. If the current is suddenly switched on,the metal ring jumps up. Explain.

$A$ coil having $100$ turns and an area of $1 \times 10^{-3} \ m^2$ is placed in a magnetic field of $1 \ Wb/m^2$. If the magnetic field is reversed,what is the total charge that flows through the circuit,given that the resistance of the circuit is $10 \ \Omega$?

Magnetic flux linked with the coil in weber is given by the equation $\phi = 5t^2 + 6t + 11$. The e.m.f. induced in the coil in the $5^{\text{th}}$ second will be (in $\text{ V}$)

$A$ coil having effective area $A$ is held with its plane normal to a magnetic field of induction $B$. The magnetic induction is quickly reduced to $25 \%$ of its initial value in $1 \ s$. The e.m.f. induced in the coil (in volt) will be