A long `U`-shaped wire of width `l` placed in a perpendicular uniform and constant magnetic field `B` (figure).A wire of length `l` is slid on the `U`-shaped wire with a constant velocity `v` towards right.The resistance of all the wires is `r` per unit length.At `t=0`, the sliding wire is close to the left edge of the fixed `U`-shaped wire.Draw an equivalent circuit diagram at time `t`, showing the induced `emf` as a battery.Calculate the current in the circuit.

Answer

B

Explanation

`epsilon=BVl`
Net resistance `R=(2l+2x)r`
`i=epsilon/R=(BVl)/((2l+2x)r)=(BVl)/(2r(l+Vt))`