The conducting rings P and Q of radius r and 3r move in opposite directions with velocity 2v and v respectively on a conducting surface S. There is a uniform magnetic field of magnitude B perpendicular to the plane of the rings. What is the potential difference between the highest points of the two rings?

Explanation

Potential difference between highest point E and lowest point A of ring P,
`V_(A)-V_(E)=B.2v.2r=4Bvr" ... (1)"`
Potential difference between highest point D and lowest point C of ring Q,
`V_(D)-V_(C)=B.v.6r=6Bvr" ... (2)"`
As the two rings move on same conducting surface S,
`V_(A)=V_(C)`
From equations (1) and (2),
`V_(D)-V_(E)=10Bvr`