A thin ring of mass 0.1kg and diameter 0.5m carrying charge q is free to rotate about an axis as shown in the figure.At t=0, time dependent magnetic field of 8t Tesla is applied vertically down on the ring.If the ring is at rest before applying magnetic field and induced magnetic effects due to rotation of the ring are neglected,the power developed by the force acting on the ring after 10sec is found to be 6.4mw .Find the charge q that the ring is carrying?