$A$ straight wire of length $L$ is bent into a semicircle. It is moved in a uniform magnetic field with speed $v$ with its diameter perpendicular to the field. The induced emf between the ends of the wire is

$A$ jet plane of wing span $20 \,m$ is travelling towards west at a speed of $400 \,ms^{-1}$. If the earth's total magnetic field is $4 \times 10^{-4} \,T$ and the dip angle is $30^{\circ}$ at that place, the voltage difference developed across the ends of the wing is (in $\,V$)

$A$ wheel of $20$ metallic spokes, each $40 \text{ cm}$ long, is rotated with a speed of $180 \text{ rev/min}$ in a plane normal to the horizontal component of Earth's magnetic field $H_{e}$ at a place. If $H_{e} = 0.4 \text{ G}$ at that place, the induced emf between the axle and the rim of the wheel is:

$A$ jet plane having a wing span of $25 \ m$ is travelling horizontally towards the east with a speed of $3600 \ km/h$. If the Earth's magnetic field at the location is $4 \times 10^{-4} \ T$ and the angle of dip is $30^{\circ}$,then the potential difference between the ends of the wing is: (in $V$)

$A$ player with a $3 \text{ m}$ long iron rod runs towards the east with a speed of $30 \text{ km/hr}$. The horizontal component of the Earth's magnetic field is $4 \times 10^{-5} \text{ Wb/m}^2$. If the player is running with the rod in horizontal and vertical positions,then the potential difference induced between the two ends of the rod in the two cases will be:

The figure shows a straight wire placed between the pole pieces of a magnet. An induced emf will be developed across the ends of the wire when it is moved towards: