Solution to task 421 from Chertov´s for extramural stud

421. A charge with linear density τ = 50 nC / m is evenly distributed over a thin ring with a radius of R = 10 cm. The ring rotates about an axis perpendicular to the plane of the ring and passing through its center, with a frequency of n = 10 s-1. Determine the magnetic moment pm due to the rotation of the ring.