ELECTRONIC PRINCIPLES - OD1647 - LESSON 1/TASK 1
material with its molecules thus aligned will have one effective
north pole, and one effective south pole. An illustration of
Weber's Theory is shown in figure 1 where a steel bar is
magnetized by stroking. When a steel bar is stroked several
times in the same direction by a magnet, the magnetic force from
the north pole of the magnet causes the molecules to align
themselves.
FIGURE 1. MOLECULAR MAGNETS (WEBER'S THEORY).
(2) Domain Theory. A more modern theory of magnetism is based
on the electron spin principle. From the study of atomic
structure, it is known that all matter is composed of vast
quantities of atoms, each atom containing one or more orbital
electrons. The electrons are considered to orbit in various
shells and subshells, depending upon their distance from the
nucleus. The structure of the atom has previously been compared
to the solar system, wherein the electrons orbiting the nucleus
correspond to the planets orbiting the sun. Along with its
orbital motion about the sun, each planet also revolves on its
axis. It. is believed that the
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