Question

A vertical conducting ring of radius R falls vertically with a speed v in a horizontal uniform magnetic field B which is perpendicular to the plane of the ring–

• A. A and B are at same potential
• B. C and D are at same potential
• C. Current flows in clockwise direction
• D. Anticlockwise in both A and B

Answer 1

Answer: (B)

C and D are at same potential

Answer 2

When the ring falls vertically, there will be an induced emf across A and B [e= Bv (2r)] Note that there will be a potential difference across any two points on the ring, line joining whom has a projected length in the horizontal plane. For example, between points 'P' and 'Q' there is a projected length 'X' in the horizontal plane.

Q Potential difference across P and Q is:

V = B vx.

But for points C and D : x = 0

Therefore Potential difference = O.