$A$ metallic ring is placed in a room. When the north pole of a magnet is brought near to it,the induced current in the ring will be

The magnetic flux linked with a coil at any instant $t$ is given by $\phi = 5t^3 - 100t + 300$. The $e.m.f.$ induced in the coil at $t = 2 \ s$ is $....... \ V$.

$A$ long solenoid having $100$ turns per $cm$ carries a current of $\frac{4}{\pi} \,A$. At the centre of it is placed a coil of $200$ turns of cross-sectional area $25 \,cm^2$ having its axis parallel to the field produced by the solenoid. When the direction of the current in the solenoid is reversed within $0.04 \,s$, the induced emf in the coil is (in $\,V$)

$A$ coil of $n$ turns and resistance $R \text{ } \Omega$ is connected in series with a resistance $R/4$. The combination is moved for time $t$ second through flux $\phi_1$ to $\phi_2$. The induced current in the circuit is

$A$ coil having an area $A_0$ is placed in a magnetic field which changes from $B_0$ to $4B_0$ in a time interval $t$. The $e.m.f.$ induced in the coil will be

Assertion : An induced current has a direction such that the magnetic field due to the current opposes the change in the magnetic flux that induces the current.
Reason : The above statement is in accordance with the conservation of energy.