Electrical Engineering for Everyone

Author: Joe H., Inflow Engineer

This post is the start of a multi-part series on electrical engineering specifically geared towards people with absolutely no science, engineering, or math background. As long as you know how to read, you should be able to follow along. We’re going to start by focusing on what electricity is, how it’s created, and how it behaves in certain situations. We’ll come back the engineering aspect once we’ve covered those basics.

To start off, we need to talk about what matter is made of. Let’s start with a piece of pure copper. If you take that piece and cut it in half, you get two smaller pieces, but both are still copper, and have all the same physical properties. Cut one of those pieces in half again, and the results will still be copper. However, if you keep cutting your copper into smaller and smaller pieces, you’ll eventually reach a point where you have the smallest bit of copper possible. That tiny piece is called an atom, and if you split a copper atom into pieces you no longer have copper. Instead, you have a collection of three types of particles, protons, neutrons, and electrons. In every atom, the protons and neutrons are lumped together in the center (nucleus) of the atom, while the electrons orbit around the outside. This figure shows a very simplified version of how atoms are put together, with protons shown in red, neutrons in black, and electrons in blue. Every atom in the universe is made up of these three particles in different combinations. For instance, a copper atom has 29 protons, 35 neutrons, and 29 electrons, while an iron atom has 26 protons, 30 neutrons, and 26 electrons.

One thing that may have caught your eye in those two example atoms I just listed is the fact that the number of protons in each atom is the same as the number of electrons. This is not a random coincidence. Protons and electrons are charged particles. Protons have a positive charge and electrons have a negative charge, so the two types of particles are attracted to each other, in much the same way that two magnets are attracted to each other. Because electrons are not attached to the nucleus of the atom they can (under the right circumstances) move from one atom to another. When this happens, the atom which has lost its electron becomes positively charged and is called an ion. Atoms can also have an extra electron forced into orbit around them, which gives the atom a negative charge, and is called an anion. Ions will readily accept electrons and anions will readily give up their extra electrons. As a result, you can have a whole pile of atoms with electrons moving between them. This movement of electrons is called electricity.

In order for electricity to be useful, you need a lot more than one electron moving and you need all of those electrons to move in one direction. Conveniently, because they are charged particles, when you move a string of electrons through a wire, they generate a magnetic field, and when you move a wire through a magnetic field, it causes the electrons in the wire to move together in one direction. This is called an electrical current. When you move a wire back and forth through a magnetic field, the electrons will flow in one direction and then the other. In fact, that’s exactly how the electricity coming out of your wall outlet is created. Because the electric current flows first in one direction and then back in the other direction, this type of electricity is called alternating current, or AC. Most of your large household electronics (lights, air conditioners, refrigerators, etc.) use this type of current. With a little bit of trickery, which we’ll cover later, you can also take electrons moving back and forth and make them move consistently in one direction. This is known as direct current or DC, and can be stored in batteries, another topic we’ll look at in another post. Because of this, DC electricity is used in computers, televisions, mobile phones, and other small electronic devices.

In both AC and DC based devices, the electrons flow through wires and special components to cause very specific reactions. As a simple example, a lightbulb is a thin coil of wire which glows when electrons pass through it. As the electrons are accepted and given up by the atoms in the wire, the atoms begin to vibrate, generating heat and light. An air conditioner, on the other hand, uses the movement of the electrons through its internal wires to create magnetic fields, which turn fans and drive compressors and pumps. The screen you’re reading this on uses resistors, capacitors, transistors, and LEDs to emit certain colors at different points on the screen. We’ll be looking at all these items and more in detail as we go through this series.

Hopefully, the concepts we’ve covered today make some degree of sense to you. I’ve simplified them quite a bit, especially with regards to atoms, so if you want to dig deeper into that subject, there’s a good primer on the development of modern atomic theory at How Stuff Works. We’re going to look at how electricity is generated in more detail in the next post, so be sure to check it out!

 

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