Magnetic field lines can reach a certain density within a material, quantified by the material’s magnetic permeability, m. The magnetic flux density, B (in Tesla or T) describes the number of field lines per unit area. The flux density decreases quickly with increasing distance from the magnet surface (Fig. 1(a)). If a magnetic material, such as soft iron, is placed in a magnetic field, the magnetic field lines are redirected through that material to take advantage of its greater permeability