Question

Two conducting rings of radii r and 2r move in opposite directions with velocities 2v and v respectively on a conducting surface . There is a uniform magnetic field of magnitude B perpendicular to plane of the rings. Find the potential difference between the highest points of the two rings.

Answer 1

An emf induced by the motion of the conductor across the magnetic field is a motional electromotive force. The equation is given by E = -vLB.  This equation is true as long as the velocity, field, and length are mutually perpendicular. The minus sign associated with the Lenz’s law.