$A$ magnetic field $4 \times 10^{-2} \, T$ acts at right angles to a coil of area $100 \, cm^2$ with $50$ turns. The average e.m.f. induced in the coil is $0.1 \, V$, when it is removed from the field in time '$t$'. The value of '$t$' is

Assertion $(A)$: It is more difficult to push a magnet into a coil with a greater number of turns.
Reason $(R)$: The $emf$ induced in a coil opposes the motion of a magnet when it is moved towards the coil.

If a copper ring is moved quickly towards the south pole of a powerful stationary bar magnet,then:

The figure shows certain wire segments joined together to form a coplanar loop. The loop is placed in a perpendicular magnetic field in the direction going into the plane of the figure. The magnitude of the field increases with time. $I_1$ and $I_2$ are the currents in the segments $ab$ and $cd$. Then,

Assertion: An $emf$ $\vec{E}$ is induced in a closed loop where magnetic flux is varied. The induced $\vec{E}$ is not a conservative field.
Reason: The line integral $\oint \vec{E} \cdot d\vec{l}$ around the closed loop is nonzero.

$A$ current-carrying infinitely long wire is kept along the diameter of a circular wire loop,without touching it. The correct statement$(s)$ is (are):
$(A)$ The emf induced in the loop is zero if the current is constant.
$(B)$ The emf induced in the loop is finite if the current is constant.
$(C)$ The emf induced in the loop is zero if the current decreases at a steady rate.
$(D)$ The emf induced in the loop is finite if the current decreases at a steady rate.