Figure (38-E26) shows a straight, long wire carrying a current i and a rod of length l coplanar with the wife and perpendicular to it. The rod moves with a constant velocity u in a direction parallel to the wire. The distance of the wire from the centre of the rod is x. Find the motional emf induced in the rod.
In this case →B varies, so we consider a small element at centre of rod of length dx at a distance x from the wire.