Two identical conducting rings `A` and `B` of radius `R` are rolling over a horizontal conducting plane with same speed `v` but in opposite direction. A constant magnetic field `B` is present pointing into the plane of paper. Then the potential difference between the highest points of the two rings is

Options

A. `0`
B. `2 BvR`
C. `4 BvR`
D. none of these

Answer

C

Explanation

`V_(2)-V_(1) = (1)/(2)B omega (2R)^(2) = 2BR(omega R) = 2BRv`

`V_(3)-V_(4) = 2BRv` But `V_(1) = V_(3) , rArr V_(2)-V_(4) = 4BR v`