A charge `q` is uniformly distributed on a non-conducting disc of radius `R`. It is rotated with an angular speed co about an axis passing through the centre of mass of the disc and perpendicular to its plane. Find the magnetic moment of the disc.

Explanation

`:' M/L=q/(2m)`
`:. M=(q/(2m))L=(q/(2m))(1omega)`
`=(q/(2m))(1/2mR^2)(omega)=(qR^2omega)/4`