As shown, a uniform magnetic field $B$ pointing out of the paper plane is confined in the shaded area of radius $r$. At a distance$R$ from the centre of the shaded area there is a point particle of mass $m$ and carrying charge $q$. The magnetic field is then quickly changed to zero. Find the speed of the particle.

 

Two identical circular coils $A$ and $B$ are placed parallel to each other with their centres on the same axis. The coil $B$ carries a current I in the clock wise direction as seen from $A$. What would be the direction of the induced current in $A$ seen from $B$ when (i) The current in $B$is increased (ii) The coil $B$ is moved towards $A$, keeping the current in $B$ constant

Consider a metal ring kept on a horizontal plane. A bar magnet is held above the ring with its length along the axis of the ring. If the magnet is dropped freely the acceleration of the falling magnet is ( $g$ is acceleration due to gravity)

In the inductive circuit given in fig. the current rises after the switch is closed. At instant, when the current is $15 \mathrm{mA}$. Then potential difference across the inductor is :-