$A$ copper disc of radius $0.1 \ m$ rotates about its centre with $10$ revolutions per second in a uniform magnetic field of $0.1 \ T$. The emf induced across the radius of the disc is

$A$ fixed rectangular conductor $ODBAC$ has negligible resistance (where $CO$ is not connected). $A$ conductor $OP$ rotates clockwise with an angular velocity $\omega$ as shown in the figure. The entire system is in a uniform magnetic field $B$ directed along the normal to the surface of the rectangular conductor $ABDC$. The conductor $OP$ is in electric contact with $ABDC$. The rotating conductor has a resistance of $\lambda$ per unit length. Find the current in the rotating conductor as it rotates by $180^{\circ}$.

$A$ conducting wire is moving towards the right in a magnetic field $B$. The direction of the induced current $i$ in the wire is shown in the figure. The direction of the magnetic field will be

$A$ conducting rod $PQ$ of length $L = 1.0\, m$ is moving with uniform speed $v = 20\, m/s$ in a uniform magnetic field $B = 4.0\, T$ directed into the paper. $A$ capacitor of capacity $C = 10\, \mu F$ is connected as shown in the figure. Then:

$A$ coil has $1000$ turns and $500 \text{ cm}^2$ as its area. The plane of the coil is placed at right angles to a magnetic induction field of $2 \times 10^{-5} \text{ Wb/m}^2$. The coil is rotated through $180^{\circ}$ in $0.2 \text{ s}$. The average emf induced in the coil,in $\text{mV}$,is

$A$ copper disc of radius $0.1 \, m$ is rotated about its centre with $10 \, rev/s$ in a uniform magnetic field of $0.1 \, T$ with its plane perpendicular to the field. The emf induced across the radius of the disc is ........... $V$.