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All electrical circuits operate from the same basic electrical principles. Like any other system on a vehicle, once you have a clear understanding of the “Basics” of how a system should work normally, then when something does go wrong, following the “Basics” will keep you on the correct troubleshooting path.
We had many very enthusiastic responses to our recent blog article that was a refresher for Ohm’s Law, so we will continue this series of articles reviewing electrical theory and circuit troubleshooting techniques.
There is much to know about electricity and this series will eventually cover a lot of ground. We are going to start with a foundation of some basic electrical theory, then move onto basic circuits and testing, and then progress into diagnosing more complex circuits and components. Some of these beginning lessons may not be very exciting, but they are a vital foundation for the rest of the series. So, please pay attention now, and I promised they will get more exciting as we progress.
In this first segment, we will cover some of the terminology used. Many of you may be familiar with some of these terms already, but just to make sure we are all speaking the same language we are going to begin this training by defining some basic electrical terms.
What is Electricity?
There are lots of definitions out there with a lot of big terms, but simply put, it is electrons moving. Electricity is the movement of electrons in the same direction … such as down a wire!
The majority of the electrical circuits that vehicle technicians deal with are Direct Current or DC, meaning that the movement of electrons is in one direction only. In an Alternating Current (AC) circuit, the flow of electrons switches direction, or alternates, flowing first in one direction then the opposite direction in a continuously repeating cycle. In either case, this flow of electrons is an energy force that can be harnessed to do work for us.
What is an Electron?
An electron is a sub-atomic particle that has a negative charge. All matter is made up of atoms. All atoms have a center or nucleus that is made up of protons and neutrons, and an outer shell of electrons orbiting the nucleus. Protons have a positive charge, while electrons have a negative charge. Most atoms in their normal state are balanced and have the same number of electrons orbiting as they have protons in their nucleus. They have the same number of positive charges and negative charges. We can, however, have atoms that are unbalanced. If an atom has more electrons than protons it has a net negative charge. If it has fewer electrons than protons it has a net positive charge. Either of these conditions creates an imbalance that wants to naturally correct itself. Atoms prefer to be in a balanced state, so the negative atoms will always be trying to get rid of their extra electrons and positive atoms will always be trying to find extra electrons. This tendency of electrons to move from where they are unwanted to where they are needed is what we use to create the movement of electrons that we call electricity. However, through chemical or mechanical methods (such as a battery or generator) we can physically add or subtract electrons from atoms and create a large imbalance or potential difference that we can put to good use. This is called Electro-Motive Force (EMF) and what is normally referred to as voltage.
come back for more….