A conducting disc of radius `r` spins about its axis an angular velocity `omega` . There is a uniform magnetic field of magnitude `B` perpendicular to the plane of the disc `C` is the centre of the disc.
(i) No emf is induced in the disc
(ii) The potential difference between `C` and the rim is `1//2Br^(2)omega`
`C` is at a higher potential than the rim
(iv) Current flows between `C` and the rim

Options

A. `(i), (iii)`
B. `(ii), (iii)`
C. `(ii), (iv)`
D. none

Answer

B

Explanation

A conducting disc is equivalent to a rod
`V_(C)-V_(A)=(1)/(2)Br^(2)omega`