Figure showns a smooth pair of thick metallic rails connected across a battery of `emf epsilon` having a negligible internal resistance.A wire `ab` of length `l` and resistance `r` can slide smoothly on the rails.The entire system lies in a horizontal plane and is immersed in a uniform vertical magnetic field `B`.At an instant `t` the wire at this instant. (b)What is the force acting on the wire at this instant. (c)Show that after some time the wire `ab` will slide with a constant velocity.Find this velocity.

Answer

A, B, C, D

Explanation

(a)`i=(epsilon-BVl)/r` clockwise
(b)`F=ilB=((epsilon-BVl)/r)lB`
( c)`F` is towards right so `v` will keep on increasing after some time current will not flow in circuit then it will move with constant velocity .`v` will be maximum (or constant) when `F=0`.
So `epsilon =BVl V=epsilon/(Bl)`