A thin semicircular conducting ring of radius `R` is falling with its plane verticle in a horizontal magnetic inducting `B`. At the position `MNQ`, the speed of the ring is `V` and the potential difference developed across the ring is

Options

A. zero
B. `BvpiR^(2)//2` and `P` is at higer potential
C. `piRBv` and `R` is at higer potential
D. `2rBv` and `R` is at higer potential

Answer

D

Explanation

The semicircular conducting ring `(PQR)` can be replaced with a straight rod of length `2r`.
hence motional emf induced across the rod
`e=B(2rV)`