$A$ wire of length $1\,m$ is moving with a velocity of $8\,m/s$ at right angles to a magnetic field of $2\,T$. The magnitude of the induced emf between the ends of the wire will be $............\,V$.

$A$ uniform magnetic field of $0.4 \ \text{T}$ acts perpendicular to a circular copper disc $20 \ \text{cm}$ in radius. The disc is rotating with a uniform angular velocity of $10 \pi \ \text{rad s}^{-1}$ about an axis passing through its centre and perpendicular to the disc. What is the potential difference developed between the axis of the disc and the rim (in $\text{V}$)? $(\pi = 3.14)$

$A$ 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 $turns$)

If a wheel with $24$ metallic spokes each $40 \ cm$ long is rotated with a speed of $180 \ rev/min$ in a plane normal to the horizontal component of earth's magnetic field, the emf induced between the axle and the rim of the wheel is $E$. If the number of spokes is made $12$ and the wheel is rotated with a speed of $90 \ rev/min$ in the same field, the induced emf is

$A$ horizontal straight conductor kept in the north-south direction falls under gravity, then

The figure shows an isosceles triangle wire frame with an apex angle equal to $\pi / 2$. The frame starts entering into the region of a uniform magnetic field $B$ with a constant velocity $v$ at $t = 0$. The longest side of the frame is perpendicular to the direction of velocity. If $i$ is the instantaneous current through the frame,then choose the alternative showing the correct variation of $i$ with time.