Practice question

**Magnetic field lines** form continuous closed loops, direction given by tangent at point, density indicates field strength. Unlike electric field lines, magnetic lines never intersect because unique field direction exists at each point, and bar magnet possesses dipole moment m = N I A directed from south to north pole inside magnet. A bar magnet cannot exert a torque on itself because torque requires an external field acting on the dipole. The field produced by the magnet itself does not generate a net rotational effect on its own structure, as internal forces cancel out. Substituting values gives It lacks an external field to act on