question_answer

Charge Q is uniformly distributed on a thin insulating ring of mass m which is initially at rest. To what angular velocity will the ring be accelerated when a magnetic field B, perpendicular to the plane of the ring, is switched on?

A) \[\frac{QB}{2m}\]         

B) \[\frac{3QB}{2m}\]

C) \[\frac{QB}{m}\]          

D) \[\frac{QB}{4m}\]