Lenz's law of electromagnetic induction corresponds to the

Then, the induced emf at the instant when radius  $r$ is. A conducting circular loop is placed in a uniform magnetic field of induction $B$ Tesla with its plane normal to the field. Now, the radius of the loop starts shrinking at the rate $\left(\frac{dr}{dt}\right)$.

Consider the statements:

(I) If magnetic field $\overrightarrow{B}=0$, then magnetic flux is also zero.

(II) If magnetic flux, $\Phi =0$, then magnetic field is also zero.

A magnet $N-S$ is suspended from a spring and when it oscillates, the magnet moves in and out of the coil $C$, Fig. $9.67$. The coil is connected to a galvanometer $G$. Then, as the magnet oscillates

One conducting $U$ -tube can slide inside another as shown in the figure, Fig $9.67\left(\mathrm{a}\right)$, maintaining electrical contacts

between the tubes. The magnetic field $B$ is perpendicular to the plane of the figure. If each tube moves towards the other at a constant speed $v$, then the emf induced in the circuit in terms of $B, l$ and $v$, where $l$ is the width of each tube will be

A small magnet $M$ is allowed to fall through a fixed horizontal conducting ring $R$. Let $g$ be the acceleration due to gravity. The acceleration of $M$ will be