1. A thin ring rotates about an axis perpendicular to a uniform magnetic field H. Its initial frequency of rotation is w. Find the time it takes the frequency to decrease to 1/e of its original value under the assumption that the energy goes into Joule heat. Display your answer in terms of conductivity, mass density of the ring, and field.

1. A thin ring rotates about an axis perpendicular to a uniform magnetic field H. Its initial frequency of rotation is w. Find the time it takes the frequency to decrease to 1/e of its original value under the assumption that the energy goes into Joule heat. Display your answer in terms of conductivity, mass density of the ring, and field.