A rectangular frame with a current was placed in a uniform magnetic field.
The magnetic field induction B is parallel to the frame plane. Area of the
frame S, current in it I.
a. Prove that the moment of forces acting on the frame is N = BM, where
M = IS is the magnetic moment of the frame.
b. Prove that the moment of forces acting on the frame in the case when
the magnetic field induction is directed as shown in the figure is equal to
→− −→→− −→
N =[M × B], where M is the magnetic moment of the frame, the modulus of
which IS, and the direction is perpendicular to the plane of the frame.