Understanding Permanent Magnets
Theory and Applications
Modern permanent magnets play a vital role in a wide
range of industrial, consumer and defense products.
Efficient use of permanent magnets in these devices
requires a basic understanding of magnetic theory. To
achieve this end it is helpful to understand that all
magnetic fields are the result of electrons in motion.
Figure 1 - Magnetic field resulting from current flow in
a coil.
In the electrical circuit, Figure 1, a DC voltage is developed
in the battery which causes a current, I, to flow through the
wires to the load. This current flow, which is the movement
of electrons between atoms in the conductor, causes a
magnetic field to be established around the wire. The
magnitude of the field is measured in ampere-turns per
meter in the International System (SI) or in oersteds in the
gram-centimeter-second (cgs) system and is designated by
the symbol H.
In permanent magnets the electrons-in-motion
phenomenon still explains the magnetic field produced
within the magnet.