Shows a wire sliding on two parallel, conducting rails placed at a separation l. A magnetic feld B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity `v` ?

Explanation

Since `F_(magnetic =i//B`
`This force produces an acceleration of the wire.`
`Since the velocity is given to be constant.Hence net force acting on the wire must be zero.