Question

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

• A. zero
• B. Bv $\pi \, R^2 \, / 2$ and M is at higher potential
• C. $\pi$ BRv and Q is at higher potential
• D. 2 RBv and Q is at higher potential

Answer 1

Answer: (D)

2 RBv and Q is at higher potential

Answer 2

Induced motional emf in MNQ is equivalent to the motional emf in an imaginary wire MQ i.e. \hspace15mm $e_{ MNQ} = e_{ MQ} = B v l = B v ( 2 R)$ \hspace19mm [ t = MQ = 2 R ] Therefore, potential difference developed across the ring is 2 RBv with Q at higher potential.