$A$ conductor $ABOCD$ moves along its bisector with a velocity of $1\, m/s$ through a perpendicular magnetic field of $1\, wb/m^2$,as shown in the figure. If all the four segments $(OB, BC, OC, CD)$ are of $1\, m$ length each,then the induced emf between points $A$ and $D$ is......$volt$.

$A$ bicycle wheel of radius $R$ has $n$ spokes. It is rotating at the rate of $F$ r.p.m. perpendicular to the horizontal component of earth's magnetic field $\vec{B}$. The e.m.f. induced between the rim and the centre of the wheel is

$A$ metal rod of length '$L$' completes the circuit as shown. The area of the circuit is perpendicular to the magnetic field '$B$'. The total resistance of the circuit is '$R$'. The force needed to move the rod in the direction as shown with a constant speed '$V$' is

In the given arrangement,a loop of width $b$ is moved with constant velocity $v$ through a uniform magnetic field $B$ restricted to a region of width $a$ (where $b > a$). The total time for which an $emf$ is induced in the circuit is:

Two parallel long straight conductors lie on a smooth surface. Two other parallel conductors rest on them at right angles so as to form a square of side $a$ initially. $A$ uniform magnetic field $B$ exists at right angles to the plane containing the conductors. They all start moving outwards with a constant velocity $v$. If $r$ is the resistance per unit length of the wire,the current in the circuit will be

$A$ circular coil of radius $10 \, cm$ and resistance of $2 \, \Omega$ is placed with its plane perpendicular to the horizontal component of the earth's magnetic field. It is rotated about its vertical diameter through $180^{\circ}$ in $0.25 \, s$. If the magnitude of the induced emf is $3.8 \times 10^{-3} \, V$, then the number of turns of the coil is (Horizontal component of earth's magnetic field at the place is $3 \times 10^{-5} \, T$) (in $turns$)