A thin non-conducting ring of mass m, radius a carrying a charge q can rotate freely about its own axis which is vertical. At the initial moment, the ring was at rest in horizontal position and no magnetic field was present. At instant t=0, a uniform magnetic field is switched on which is vertically downward and increases with time according to the law B=B0t. Neglecting magnetism induced due to rotational motion of ring.
Find instantaneous power developed by electric force acting on the ring at t=1 s.
(a) 14m2q2B02a2
(b) 8mq2B02a2
(c) m3q2B02a2
(d) 4mq2B02a2