What Are Electrical Circuits
Throughout your training as an electrician you will be exposed to more and more complex electrical circuits. In its’ simplest form a circuit is just a path for electrons to travel along, however like everything it is much more complex than that when using electricity to do work for us.
In the new theory of electricity, electrons flowing along a wire has been replaced with Hole Theory. It is beyond this site to explain the difference and for basic understanding of electrical circuits not needed. An apprentice will be taught all about this during their formal training and then put the knowledge to use when working in the field.
In its’ simplest you don’t get electrical flow unless you have a potential difference. Us old timers like to use the water analogy to explain this. Lets’ assume you have a bucket of water sitting on the ground. If you knock it over you get the floor wet and maybe your feet. Not nearly as bad as If you take a bucket of water and raise it off the ground six feet and then knock it over. But if you do not knock it over then you now have a bucket of water in the air and nothing else. The water is not flowing out of the bucket but is sitting there ready to flow instantly if something knocks the bucket over. This is what we call potential.
If you do knock the bucket over you’re going to get wet head to toe or certainly a lot more than if you just knocked it over when it was sitting on the ground. The higher you raise the bucket the greater the speed that the water flows when it has a chance to fall and the greater area it will soak. Each time you raise the bucket you increase the potential.
Voltage is how we measure potential for electricity and the higher the voltage the greater the potential. However if you don’t have a circuit (path) for the electricity then it is just like a bucket of water sitting in the air, nothing happening, but it could! With electricity the higher the voltage the greater the likely hood that something will occur but lets ignore that for the moment.
So like I said In order to get electricity to flow you need a circuit. If you knock the bucket full of water over that is up off the ground then the air is the conductor that the water flows through. Because you knocked the bucket over all the water flows out at once (almost at once) and the air does not hinder it much as it falls to the ground. Although you have a circuit; water off the ground (potential or source), air to flow through (conductor), the circuit is really a short circuit as nothing impedes the flow of water and it all comes crashing down at once. Not a good thing.
It is the same for electricity. If you have a source and a conductor then you are missing the one element that stops the whole thing from burning up and that is resistance (load).
If I fill the air with Scotty paper towel below the bucket of water then the water would not crash immediately to the earth but move slowly through the paper towel. Some would stay in the paper towel but most would work its way to the earth buy drips and drops in a nice orderly fashion.
The same is true with electricity. If I put resistance somewhere along the conductor then the potential will discharge in a nice orderly fashion. This resistance comes in many ways but think of it as the load or device that does the work (motor, stove element, microwave etc).
At its simplest that is all a electrical circuit is.