A thin non-conducting ring 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 and no magnetic field was present. At instant `t = 0`, a uniform magnetic field is switched on which is vertically downwards and increase with time according to the law `B = B_(0)t`. Neglecting magnetism induced due to totational motion of the ring. Now answer the following questions.
The power developed by the forces acting on the ring, as a function of time :

Options

A. `(E^(2) q^(2))/(2m)t`
B. `(E^(2) q^(2))/(m)t`
C. `(2E^(2)q^(2))/(m)t`
D. `(sqrt(2)E^(2) q^(2))/(m)t`

Answer

B