I need help to solve this problem and also please draw a free body diagram for the problem.

A thin, insulating ring has radius R = 25 cm and linear charge density A = +31pC/m. The ring is spinning with angular speed w = 3.5rad/s about its center. In this region of space, a uniform magnetic field B = 760 mT points parallel to the plane of the ring. What is the magnitude of the magnetic torque 7 that the magnetic field applies to the ring at this moment? (Hint: to determine the current associated with the rotating ring, think about how much charge passes through a given point during each rotational period.) For the limit check, investigate what happens to 7 if the ring is barely rotating (i.e., w 0)