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An Introduction To Electronicsby Al Margolis, founder www.HobbyEngineering.comChapter 1: IntroductionElectronics is the art and science of directing electrons to do useful work. An electron is a sub-atomic particle that carries a charge of energy. Each electron is so small that it can carry only a tiny bit of energy. The charge of electrons is measured in coulombs. One coulomb is the charge carried by 6,250,000,000,000,000,000 electrons. That's 6.25 X 10^^18 electrons for you math whizzes. Every good electronics text begins with this definition. The term coulomb is rarely used past page 3 of electronics texts and almost never in the actual building of electronic circuits. Electrons are so small that you can't see them. Each electron is so weak that it takes billions to do the tiniest bit of work. The point of discussing coulombs is to remind you that there are so many electrons that they can do serious work or harm. One drop of water doesn't have much influence on the world. A small stream of water drops for a few millennium can dig the Grand Canyon. A large stream of water (called a flood) can wipe out a city in a few hours. Electrons are just like that but invisible to the naked eye. A boring piece of copper wire plugged into the wall doesn't look threatening, but in can stop your heart or start a fire in a small fraction of a second if not properly handled. Unlike floods, it is fairly easy to control the flow of electrons in such a way as to do useful work. We do that all the time by turning on everything from light switches to televisions to computers. Its easy to be fascinated by the useful capability of electrons. Its important to remember that they can also be dangerous killers. Millions of people work with electronics every day and accidents are very rare. Working with electronics is probably safer than playing sports and definitely safer than driving a car. The way to keep it that way is to always keep in mind that it can be extremely dangerous if you don't follow the rules of safety. Electronics is the art and science of getting electrons to move in the way we want to do useful work. Electrons are a component of atoms. There are about 100 different kinds of atoms. Each different kind is called an element. Some elements have structures that hold tight to their electrons so that it is very hard to make the electrons move. Materials made with these elements are called insulators. Other elements have structures that allow their electrons to move easily. Materials made with these elements are called conductors. Most real world materials are made from combinations of elements. You must study the material to determine whether it is primarily a conductor or an insulator. Absolutely pure water is a very good insulator. Add a dash of salt and it becomes a very good conductor even though it looks exactly the same. That is why it is such a bad idea to talk on the phone while in the bathtub. It is also a reminder that when it comes to electricity the only time we can rely on our eyes is when we are looking at an appropriate piece of test equipment (more on this later). End of ChapterThis tutorial is a work in progress. If you found it interesting, awful or incomplete please let me know by sending email toal@biznode.com. Chapter two will be published as soon as I can manage. |
The content on this page was updated on 09/25/2004