Electricity is one of the most difficult fields that today’s automotive technician will be asked to work with. Vehicles have become increasingly more electrically complex and equipped with more and more electrical components than ever before. No longer are hydraulic and vacuum controls and components considered commonplace. It is therefore merely common sense that the average technician needs to be knowledgeable and familiar with electricity and the principles of which it operates.
Most electrical test procedures are described in the various shop manuals that are readily available, both on line and the practically outdated shop manual. These procedures, most often require specialized test equipment and an assumption that the technician has a general familiarity with how to operate said equipment. A basic understanding of electricity and the nature of it’s properties is essential. This is what this article is designed to explain.
All matter in the universe is constructed of atoms. Each atom is made of smaller parts called protons, electrons and neutrons. A physical model of a typical atom is often compared to a solar system. The center of the atom, called the nucleus, is made of neutrons and protons. Neutrons have a neutral electrical charge, while protons have a positive electrical charge. The electrons in an atom spin rapidly around the nucleus like the planets orbit the sun. Electrons are charged negatively and weigh 1/1800 as much as a proton or a neutron.
Atoms in a solid are mostly space much like our solar system. Picture in your mind, a spinning fan with only 2 blades. When the fan spins fast enough it appears to be a solid surface. If a rubber ball was tossed into a spinning fan it would bounce back as if it hit a solid surface even though the fan is mostly space. The atom acts in much the same way, the electrons spin around the nucleus at speeds as high as 4000 miles per second. Thus the atom appears to be a solid.
When the number of electrons in an atom is equal to the number of protons, the atom has a neutral charge because the electrons are negative and the protons are positive. So if an atom has more electrons than protons it would have a negative charge, and if an atom has more protons than electrons it would have a positive charge. Electrons orbiting around the nucleus are orbiting at different distances.
Picture several satellites orbiting the earth at various distances. Some satellites are so close to the earth’s surface that they are able to orbit the earth in one hour. Other satellites are so far away from the earth, they take 24 hours to complete an orbit. The electrons in an atom that are farthest away from the nucleus are loosely bound while the electrons that orbit close to the nucleus are tightly bound. In many material objects the outer electrons can be removed from and added to other atoms because of their far distance from the nucleus.
An atom that looses an electron will have more protons (+) than electrons (-) causing the atom to have a positive charge. An atom that gains an electron will have more electrons (-) than protons (+) and thus would have a negative charge. Atoms with either extra or missing electrons are called ions. Thus, the nature of basic positive and negatively charged particles.