Lesson 1/Learning Event 1
FIGURE 2. FREE ELECTRON.
Now, let's go back to our magnifying glass and reduce its power so that we can see several atoms of
copper in the viewing area. You can now see that some electrons moving in the outer circles of the
atoms do not always stay in the same atom. Instead, they move haphazardly from atom to atom.
They are known as free electrons, and they are the ones we are most interested in for our study of
automotive electricity.
As some of the free electrons move out of their orbits (paths), the atom will have more protons
than it does electrons. Since the protons have a positive charge, this gives the atom a positive
charge. If the free electrons move to an atom that already has enough electrons, that atom will be
negatively charged, since it will have a surplus of electrons. A negatively charged body repels
electrons while a positively charged body attracts electrons.
ELECTRON MOTION
In automotive electricity, we are most interested in the mass movement of electrons through an
item, such as a wire. Such a movement of electrons is known as ELECTRIC CURRENT just as
the flow of water in a stream is known as current.
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