The magnitude of induced emf is directly proportional to the rate of change of magnetic flux linked with the coil. This statement is known as

The magnetic flux linked with a coil is given by the equation $\phi$ (in webers) = $8t^2 + 3t + 5$. The induced $e.m.f.$ in the coil at the $4^{th}$ second will be.......$units$.

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.

$A$ circular loop of radius $r$ is moved away from a current-carrying wire. The induced current in the circular loop will be:

$A$ current-carrying solenoid is approaching a conducting loop as shown in the figure. The direction of the induced current as observed by an observer on the other side of the loop will be

$A$ coil has $1,000$ turns and $500 \, cm^2$ as its area. The plane of the coil is placed at right angles to a magnetic induction field of $2 \times 10^{-5} \, Wb/m^2$. The coil is rotated through $180^o$ in $0.2 \, s$. The average $e.m.f.$ induced in the coil,in milli-volts,is