A thin semicircular conducting ring of radius R is falling with its plane vertical in a horizontal magnetic induction B fig. (12). At the position MNQ

the speed of ring is V and potential difference developed across the ring is

• A

  $\frac{{\mathrm{BV\pi r}}^2}{2}$ and M is at higher potential

• B

  $\mathrm{\pi }$ R B V and Q is at higher potential

• C

  $\mathrm{\pi }$ R B V and Q is at higher  potential

• D

  2 R B V and Q is at higher potential