Physics of Magnetism

CHAPTER 8. SOME BASIC CONCEPTS AND UNITS 83

is produced by both the conduction and the Amperian (atomic) currents, while has its

point (ii) appears to be more general. It is clear that those advocating the primacy of

source exclusively in external conduction currents. Hence, the analogy considered under
have
an excellent viewpoint although historically they are at a disadvantage, because the magnetic
pole approach has traditionally been used in magnetostatics by analogy with electrostatics.

preferred because the desired quantity is The relevant field

sample is the internal field, which originates not only from the external field

in a magnetized

In fact, for the characterization of magnetic materials the traditional approach is usually

but

has to be corrected by

the demagnetizing field

also from the stray- or self-field of the magnetized body. Thus,
where is the demagnetizing factor and depends
on the sample geometry, as shown in Table 8.1. A more detailed discussion regarding these
matters can be found in articles written by Cohen and Giacomo (1987), Goldfarb (1992),
and Hilscher (2001).

References

Cohen, E. R. and Giacomo, P. (1987) Symbols, units, nomenclature and fundamental constants in physics, Physica

A, 146, 1.

Goldfarb, R. B. (1992) Demagnetizing factors, in J. Evetts (Ed.) Concise encyclopedia of magnetic and

superconducting materials, Oxford: Pergamon, p. 103–104.

Hilscher, G. (2001) in Encyclopedia of materials: science and technology, Amsterdam: Elsevier Science.