My name is Bernhard Baumgartner and some of you may already know me from other basic articles. Igor has asked me to write an article or rather a series of articles for you in order to give you a better understanding of what can be a rather dry subject: “Basic electrical engineering”. The background is clear, because in a few days’ time it will be all about graphics cards, load peaks and other subtleties that require a certain amount of basic knowledge. And to make sure you get the full picture when the time comes, here are a few basics in advance. Of course, some will now shake their heads knowingly and think, what’s this all about? But for the inquiring youth there is (hopefully) some new knowledge and for the rest at least a little refresher before the big bad boys come and throw colorful pixels at us again.
My approach to explaining this topic should be relaxed and easy to understand, always peppered with examples from real life and related to computers, which we all feel so comfortable with. I can still remember my first lesson in electrical engineering at vocational school very clearly and I hated it. I really did! Over time, however, this discipline became more and more interesting, so I even changed my specialization to electronics during my vocational training. After three years, I had my journeyman’s certificate as an “automotive mechatronics technician for vehicle communication technology” and from then on I went into automotive development, including training as an instructor. What I didn’t like at the beginning has developed into a real passion, even my professional focus. In the course of this article, I hope to infect someone after all.
So sit down, put your feet up, grab a cookie and have fun on Monday!
Bohr’s atomic model
When you ask people what electricity, electronics and current actually are and that you should explain it to five-year-olds, it quickly becomes clear that it’s not that easy. Yes, electricity is to a large extent quite abstract. You can’t smell electrons, you generally can’t see or hear them either – homo sapiens simply don’t have the sensors for it. At most, if you stick your finger in the socket. This is also the reason why electricity is really dangerous! So if you ever want to do handicrafts or are interested in the subject, make sure you familiarize yourself with the five safety rules and the effects of electricity on health beforehand!
If we want to understand electricity, we can use an impressive thought experiment: Imagine you are sitting in an electrical engineering laboratory and there is a piece of cable on the table in front of you. If we were to zoom in closer and closer to the cable with our eyes, we would soon see that the cable is not a single, solid conductor, but consists of small, individual strands. On closer inspection, these copper strands have a textured surface with sharply defined areas. Some parts are lighter and some darker; we have now arrived at the grain level. If we zoom in further, we see a 3D grid, where each connecting point is a copper atom. We are now at the atomic level and that is exactly where we need to be to understand what electricity actually is and how it works.
If we look at the picture, we see the nucleus (nucleus, red and green), which consists of an equal number of neutrons (neutral charge, green) and protons (positive charge, red). If the nucleus is isolated from the rest of the atom, its total charge is positive. The electrons (blue), which orbit the nucleus, serve as the negative charge. The orbits are not fixed orbits, as in a satellite, for example, but should rather be seen as “probability spaces”. If we add the negative electrons to the positive atomic nucleus, we get a neutral atom because the charges are balanced. It is striking that there are some electrons that orbit closer to the nucleus and others further away from it.
This has to do with energy absorption and release. If an electron has a high energy (eV / electron volt), it can orbit the nucleus further out. If it has less energy, it moves closer to the nucleus. As a mnemonic, you can think of it like spaceships in Earth orbit: A spaceship with powerful propulsion can leave the Earth’s gravitational field further than a fart ship that only has a Chinese banger on the back. The most important aspect of this finding for us is that those interested in electronics only need to remember that there are free electrons (FE, blue) on the outermost orbit and can therefore jump back and forth between neighboring atomic nuclei. It could be said that a small amount of energy absorption is enough for these free, unbound electrons to move to the next atomic nucleus. They don’t have far to go, they are already on the outside anyway..
Let us now consider a series of cubes, each of whose corners is a copper atom. If we now apply an electrical potential of 0V to one end and a potential of 12 volts to the other, the free electrons begin to move in a directional motion (red arrows). This is exactly what electricity is: the directional movement of electrons. BRUTAL!
Brain download: Electric current is the directional movement of free electrons in conductive materials! Electrons always have a negative potential, while the atomic nucleus is positively charged!
