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. Superconductors exhibit perfect diamagnetism (Meissner effect), expelling all magnetic field lines from their interior by inducing surface currents that create an opposing field. This repulsion allows them to levitate a magnet, a phenomenon unique to their zero permeability state. Substituting values gives Complete expulsion of magnetic fields, which matches expected magnitude for this