A copper wire bent in the shape of a semicircle of radius r translates in its plane with a constant velocity v. A uniform magnetic field B exists in the direction perpendicular to the plane of the wire. Find the emf induced between the ends of the wire if (a) the velocity is perpendicular ot the diameter joining free ends, (b) the velocity is parallel to this diameter.

Explanation

A wire other that straight wire can be repaced by a straigh wire by joined initial and final points.
(b) `e=0` , because `vec(v)||vec(l)`