ABSTRACT
Magnetism is a term to describe how materials respond to an applied magnetic šeld. Common forms of magnetism are paramagnetism, diamagnetism, ferromagnetism, anti-ferromagnetism, and ferrimagnetism (Okuhata, 1999). In a magnetic šeld, all materials are in·uenced, more or less, and express different magnetism. There are two magnetic šelds, the B-šeld and the H-šeld. The B-šeld is usually called the magnetic ·ux density but goes also under different names, such as the magnetic šeld and magnetic induction. The H-šeld or magnetic šeld is also known under other names: magnetizing šeld, magnetic šeld strength, and magnetic šeld intensity. In this paper, we use either B-šeld or magnetic ·ux density for the B-šeld and H-šeld and magnetic šeld for the H-šeld. The B-šeld is in·uenced by matter, and the relationship between B and H is
B = μ · H = μr · μ0 · H (7.1)
(Benenson et al., 2001), where µ is the permeability, µr is relative permeability, and µ0 is vacuum permeability (also called magnetic constant or permeability of free space). The magnetic susceptibility (xm) is
xm = μr – 1 (7.2)
The different forms of magnetism and their magnetic susceptibility and relative permeability are shown in Table 7.1.
