The instantaneous value of the emf induced in the wire will be. A horizontal straight wire $20 \mathrm{m}$ long extending from east to west is falling with a speed of $5{ \mathrm{ms}}^{-1}$, at right angle to the horizontal component of the earth's magnetic field $0.03\times {10}^{-4} {\mathrm{Wbm}}^{-2}.$

A rectangular loop has a sliding connector $PQ$ of length $l$ and resistance $R\Omega$ and it is moving with a speed $v$ as shown in Fig. $9.70$. The set up is placed in a uniform magnetic field going into the plane of the paper. The three currents $I_1,I_2$ and $l$ are

A horizontal ring of radius $r$ and resistance $R$ moves without friction over two horizontal rail of no resistance. The left ends of two rails joined by a wire $PQ$ of no resistance. There is a vertical, uniform magnetic field $B$ directed into the page, Fig.$9.71$. The current in the section $PQ$, when the speed of the ring is $v$, is

In a uniform magnetic field of inductance $B$, a wire in the form of semicircular of radius $r$ rotates about the diameter of the circle with angular frequency $\omega$. If the total resistance of the circuit is $R$, the mean power generated per period of rotation is