Question
Question: Two identical conducting ring A and B of radius R are in pure rolling over a horizontal conducting p...
Two identical conducting ring A and B of radius R are in pure rolling over a horizontal conducting plane with same speed (of center of mass) v but in opposite direction. A constant magnetic field B is present pointing inside the plane of paper. Then the potential difference between the highest points of the two rings, is:
A
Zero
B
2BvR
C
4BvR
D
None of these
Answer
Zero
Explanation
Solution
Considering a projected length 2R on the ring in vertical plane. This length will move at a speed v perpendicular to the field.
This results in an induced emf:
e = Bv (2R) in the ring
In Ring ‘‘A’’ : eA = B(–V (2R)
In Ring ‘‘B’’: eB = B(V) (2R) –B (–V) (2R) = 4 BvR
Note- There will be no potential difference across a diameter due
to rotation.