A thin semicircular conducting ring of radius `R` is falling with its plane vertical in a horizontal magnetic induction `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 `M` is at higer potential
C. `piRBV` and `Q` is at higer potential
D. `2RBV` and `Q` is at higer potential

Answer

D

Explanation

Rate of decrease of area of the semicircular ring `(dA)/(dt)=(2R)V`
According to Faraday's law of induction induced emf `e=-(dvarphi)/(dt)=-B(dA)/(dt)=-B(2RV)`
The induced current in the must generate magnetic field in the upward direction. thus `Q` is at higer potential