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ELECTRICAL FUNDAMENTALS
General
Electricity is a form of energy called electrical
energy. It is sometimes called an "unseen" force
because the energy itself cannot be seen, heard,
touched, or smelled.
However, the effects of electricity can be seen ...
a lamp gives off light; a motor turns; a cigarette
lighter gets red hot; a buzzer makes noise.

The effects of electricity can also beheard, felt,
and smelled. A loud crack of lightning is easily
heard, while a fuse "blowing" may sound like a soft
"pop" or "snap." With electricity flowing through
them, some insulated wires may feel "warm" and
bare wires may produce a "tingling" or, worse,
quite a "shock." And, of course, the odor of burned
wire insulation is easily smelled.

P age 1

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ELECTRICAL FUNDAMENTALS
Electron Theory

ATOMIC STRUCTURE

Electron theory helps to explain electricity. The
basic building block for matter, anything that has
mass and occupies space, is the atom. All matter solid, liquid, or gas - is made up of molecules, or
atoms joined together. These atoms are the
smallest particles into which an element or
substance can bedivided without losing its
properties. There are only about 100 different
atoms that make up everything in our world. The
features that make one atom different from another
also determine its electrical properties.

An atom is like a tiny solar system. The center is
called the nucleus, made up of tiny particles called
protons and neutrons. The nucleus is surrounded
by clouds of other tinyparticles called electrons.
The electrons rotate about the nucleus in fixed
paths called shells or rings.
Hydrogen has the simplest atom with one proton in
the nucleus and one electron rotating around it.
Copper is more complex with 29 electrons in four
different rings rotating around a nucleus that has
29 protons and 29 neutrons. Other elements have
different atomic structures.

P age2

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ELECTRICAL FUNDAMENTALS
ATOMS AND ELECTRICAL CHARGES
Each atomic particle has an electrical charge.
Electrons have a negative (-) charge. Protons
have a positive charge. Neutrons have no charge;
they are neutral.
In a balanced atom, the number of electrons
equals the number of protons. The balance of the
opposing negative andpositive charges holds the
atom together. Like charges repel, unlike charges
attract. The positive protons hold the electrons in
orbit. Centrifugal force prevents the electrons
from moving inward. And, the neutrons cancel the
repelling force between protons to hold the atom's
core together.

POSITIVE AND NEGATIVE IONS
If an atom gains electrons, it becomes a negative
ion . If an atomloses electrons, it becomes a
positive ion. Positive ions attract electrons from
neighboring atoms to become balanced. This
causes electron flow.

ELECTRON FLOW
The number of electrons in the outer orbit
( valence shell or ring) determines the atom's
ability to conduct electricity. Electrons in the inner
rings are closer to the core, strongly attracted to
the protons, and are called b oundelectrons .
Electrons in the outer ring are further away from
the core, less strongly attracted to the protons,
and are called f ree electrons .
Electrons can be freed by forces such as friction,
heat, light, pressure, chemical action, or magnetic
action. These freed electrons move away from the
e lectromotive force , or EMF ("electron moving
force"), from one atom to the next. A streamof
free electrons forms an electrical c urrent .

P age 3

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ELECTRICAL FUNDAMENTALS
CONDUCTORS, INSULATORS,
SEMICONDUCTORS
The electrical properties of various materials are
determined by the number of electrons in the outer
ring of their atoms.
• CONDUCTORS - Materials with 1 to 3 electrons in
the atom's outer ring make good...