$A$ metallic square loop $ABCD$ is moving in its own plane with velocity $v$ in a uniform magnetic field perpendicular to its plane as shown in the figure. An electric field is induced:

$A$ metal disc of radius $a = 10 \ cm$ rotates with a constant angular speed of $\omega = 200 \ rad \ s^{-1}$ about its axis. The potential difference between the centre and the rim of the disc under a uniform magnetic field $B = 5 \ mT$ directed perpendicular to the disc is: (in $mV$)

$A$ pair of parallel conducting rails lie at a right angle to a uniform magnetic field of $2.0\, T$ as shown in the figure. Two resistors,$10\,\Omega$ and $5\,\Omega$,slide without friction along the rails. The distance between the conducting rails is $0.1\, m$. Then:

Two conducting rings $P$ and $Q$ of radii $r$ and $2r$ rotate uniformly in opposite directions with centre of mass velocities $2v$ and $v$ respectively on a conducting surface $S$. There is a uniform magnetic field of magnitude $B$ perpendicular to the plane of the rings. The potential difference between the highest points of the two rings is

$A$ $800$ turn coil of effective area $0.05\; m^{2}$ is kept perpendicular to a magnetic field $5 \times 10^{-5}\; T$. When the plane of the coil is rotated by $90^{\circ}$ around any of its coplanar axes in $0.1\; s$,the $emf$ induced in the coil will be.....$V$

$A$ wire having mass $m$ and length $l$ can freely slide on a pair of parallel smooth horizontal rails placed in a vertical magnetic field $B$. The rails are connected by a capacitor of capacitance $C$. The electric resistance of the rails and the wire is zero. If a constant force $F$ acts on the wire as shown in the figure,then the acceleration of the wire is given by: