A vertical ring of radius `r` and resistance on `R` falls vertically. It is in contact with two vertical rails which are joined at the top. The rails are without friction and resistance. There is a horizontal uniform, magnetic field of magnitude `B` perpendicular to the plane of the ring and the rails. When the speed of the ring is `v` , the current in the section `PQ` is

Options

A. zero.
B. `2Brv//R`
C. `4Brv//R`
D. `8Brv//R`

Explanation

`i=(Bv(2r))/(R_(eq))`, where `R_(eq)=((R//2)(R//2))/(R//2+R//2)=R//4`