A thin non-conducting ring of mass m, radius a, and charge q can rotate freely about its own vertical axis. Initially, the ring is at rest in a horizontal position and no magnetic field is present. At t=0, a uniform magnetic field is switched on vertically downward and increases according to B=B0t. Neglect magnetism induced due to rotational motion of the ring.
The angular acceleration of the ring is:
(1) (a) 2mqB0
(2) (c) mqB0
(3) (b) 4mqB0
(4) (d) m2qB0