A rigid circular loop has a radius of 0.20 m and is in the xy-plane. The loop carries a
clockwise current I. The magnitude of the magnetic moment of the loop is 0.75 A.m2
.
A uniform external magnetic field, B = 0.20 T is directed parallel to the plane of the
loop. An external torque changes the orientation of the loop from one of lowest potential energy to one of highest potential energy. Calculate the work done by this external
torque.