A circular copper-ring of radius r travels in its plane with a constant velocity v . A uniform magnetic field B is present in the space, directed perpendicular to the plane of the ring. Considering various pairs of diametrically opposite points on the ring, between which pair of points is the emf minimum, and what is the value of this minimum emf?

Step-by-step solution

The motional emf induced between any two points of a conductor moving in a uniform magnetic field is given by = ( v B ) l , where l is the displacement vector between the two points. Here, v is in the plane of the ring and B is perpendicular to the plane. Thus, v B is a vector in the plane of the ring, perpendicular to the velocity v , with magnitude vB . For diametrically opposite points, the displacement vector l has a magnitude of 2r . The induced emf is = vB(2r) , where is the angle between v B and l . For the