ABSTRACT
The direction of the magnetic lines of force changes in the presence of the dia- and paramagnetic substances: the paramagnetics make the applied field stronger, while the diamagnetics make it weaker. Experimentally determined parameters are usually the average magnetic susceptibility and its anisotropy. The temperature-independent paramagnetism as well as diamagnetism is not related to any permanent magnetic moment of a particle and is induced in it by an external magnetic field. The counteraction of two equilibrating processes is in the basis of the Curie law and the Curie-Weiss law: one of them is related to an ordering of the magnetic moments of unpaired electrons, aligning along the field, and the other one is connected to the Brownian thermal motion of the molecules. The magnetic anisotropy might be due to not only the orbital angular momentum in the ground state, but also due to temperature independent paramagnetism from some excited state, which also can possess the orbital angular momentum.
