ABSTRACT
The mathematical concepts of magnetic poles and Amperian currents provide a framework for calculating the magnetization and magnetic fields generated by magnetic materials. When going on to consider magnetic materials, it is first necessary to define quantities that represent the response of these materials to the magnetic field. These quantities are magnetic moment and magnetization. In view of the fact that the magnetization and the magnetic field point in opposite directions inside a magnetized material of finite dimensions, due to the presence of the magnetic dipole moment, it is possible to define a demagnetizing field, which is present whenever magnetic poles are created in a material. The current loop has no effective length, while the dipole has no effective cross-sectional area. If a material has elementary atomic magnetic dipoles per unit volume each of magnetic moment, then the magnetic moment per unit volume of the material when all these moments are aligned parallel is termed the saturation magnetization.
