Chevrolet TrailBlazer, Service Manual, Page: 338 / 677

Basic Electricity
WARNING
To avoid personal injury and/or vehicle damage, refer to the service precautions at the
beginning of this section.
Basic Electrical Theory
Electricity is based on the principle that electrons are attracted to protons. Electron
movement can be created when the atomic structure of a material is forced to become
imbalanced. Atoms are made up of an equal quantity of positively and negatively charged
parts. The nucleus contains protons, with a positive charge, and neutrons with a neutral
charge. The negative charge or electrons constantly orbit around the nucleus in valence
rings.
If an electron were to be separated from an atom it would assume a net positive charge
and become a positive ion. On the other hand, if an element were to "acquire" an electron
it would have a net negative charge and become a negative ion. If we were to store these
positive and negative ions in a container we would have a power source, or battery.
Voltage
Electricity is the flow of electrons from a greater potential (more electrons) to a lesser
potential (less electrons). If a path were provided for the electrons from the negative ions
to flow to the positive ions each ion could then maintain its balanced condition. The
pressure that the electrons exert when returning to its source is called voltage. When
voltage (V) is measured with a voltmeter, the value displayed represents the attractive
force, or electromotive force available to get the atoms in balance again.
Amperage
Amperage is a measure of the actually quantity of electrons that flow from the net negative
charge to the net positive charge. This movement of electrons, or current, is what actually
does the work in an electrical circuit. Current flow is measured in units of Amperes, or
Amps (A). Amperage is a time-based unit. One Amp is equal to 6.28 x 10
28
electrons
moving past one point in one second. When an ammeter is connected in series with a
circuit, the actual quantity of electrons that flow through the circuit are measured.
Resistance
Resistance is an elemen
t’s ability to oppose current flow. The resistance of an element
depends upon its atomic structure- specifically how many electrons are held in orbit in the
outermost or valence ring. to eight electrons can occupy the valence ring of an atom.
When fewer electrons are present in the valence ring there is more "room" for electrons to
flow across the surface of an atom.
Electrically speaking, elements can be categorized as conductors, insulators and semi-
conductors. Conductors are elements with between one and three electrons in their