3.17 The Dipole in a Uniform Magnetic Field

A magnetic dipole placed in the direction of field experiences no resultant force or torque, since the force on both the north and south poles are equal and opposite force along same line. But if the dipole is placed inclined to the field then both the north and south poles experiences equal and opposite force with different line of action. Then the magnetic dipole experience a resultant torque.

If m is the moment of magnet and B is the magnetic field intensity, then torque is given by

T=mxB

ie., T=mBsin theta..