If we double the velocity of a rod moving in a uniform magnetic field, then the induced $emf$ will increase by how many times?

$A$ wire $ab$ of length $l$,mass $m$,and resistance $R$ slides on a smooth,thick pair of metallic rails joined at the bottom as shown in the figure. The plane of the rails makes an angle $\theta$ with the horizontal. $A$ vertical magnetic field $B$ exists in the region. If the wire slides on the rails at a constant speed $v$,then which of the following can be correct for $B$?

$A$ square loop of side $a$ and resistance $R$ is moved in a region of uniform magnetic field $B$ (the loop remaining completely inside the field) with a velocity $v$ through a distance $x$. The work done is:

$A$ conducting wire is dropped along the east-west direction. Then,

$A$ square loop of side $20\, {cm}$ and resistance $1\, \Omega$ is moved towards the right with a constant speed ${v}_{0}$. The right arm of the loop is in a uniform magnetic field of $5\, {T}$. The field is perpendicular to the plane of the loop and is directed into it. The loop is connected to a network of resistors,each of value $4\, \Omega$. What should be the value of ${v}_{0}$ so that a steady current of $2\, {mA}$ flows in the loop?

Two straight conducting plates form an angle $\theta$ where their ends are joined. $A$ conducting bar in contact with the plates and forming an isosceles triangle with them starts at the vertex at time $t=0$ and moves with constant velocity $\vec{v}$ to the right as shown in the figure. $A$ magnetic field $\vec{B}$ points out of the page. The magnitude of the emf induced at $t=1 \text{ s}$ will be