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A thin semicircular conducting ring (PQR...

A thin semicircular conducting ring (PQR) of radius r is falling with its plane vertical in a horizontal magnetic field B, as shown in figure. The potential difference developed across the ring when its speed is v, is:

A

zero

B

Bv `pir^2//2` and P is at higher potential

C

`piBv` and R is at higher potential

D

2rBv and R is at higher potential

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