Electrical Myth Busting
There are some electrical myths out there that deserve to be busted. I thought it might be interesting to start a discussion on electrical fundamentals. I'm by no means an authority on this but over the last few years, I have learned that some of the electrical concepts I was taught years ago were not quite accurate. I'm interested in fleshing out these issues to further my understanding of electricity and hopefully help others in the process.
- Current takes the path of least resistance. FALSE
This has been taught in the automotive and the electrical fields for years but it is false, or at the least, very misleading. In reality, current will take ALL possible paths at the same time. The only difference will be the amount of current that flows in each leg of the circuit, depending on it's particular resistance or impedance.
2. Current wants to go to ground. FALSE
Current always wants to return to the source. Electrons need to return to whatever source they originated from. The current will always return to the source through whatever path possible. Ground in an automobile is simply a path for electrons to get back to the source. (Battery/Alternator)
This is an important concept and it is why strange things happen when a particular circuit loses it's ground connection. When that circuit is activated, the electrons want to flow through the load and then return to the source. If the usual ground path is open, the current can find it's way back to the source through other circuits. If there is a path available, the current will take it.
I have a link to a video that explains some of these concepts in great detail. It's geared towards electricians but much of the information is applicable to automotive also. The instructor is Mike Holt and he is like the John Thornton of the electrical industry. The video is about an hour and 13 min and it's worth every second.
P.S. After watching this video you will understand exactly what that little green lead in light fixtures and fans etc. is there for and how it works.
I have one that is sort of related to your #2.
Many techs think(or worse,have been taught) that voltage travels from positive to negative in an automotive system.
I think you meant to say "current" but correct me if i'm wrong. I believe your talking about "conventional" flow theory vs "electron" flow theory.
I agree that conventional theory (positive to negative) is how it's always been taught but it's not technically accurate. In simple electrical circuits like light bulbs etc. it really doesn't matter if you apply conventional or electron theory, however, when you have semiconductor components in a circuit, it makes a big difference. It's very helpful to really understand what's going on.
Here's a nice explanation of this issue allaboutcircuits.com/textbook/direc…
Also, I don't know if you have seen it before but Vince Fishelli has done a great series on ground circuits in automobiles. There is lots of great info there. Here is a link to the first part of the series.