Usually each week something happens that spurs me to think of an interesting article to write for you here about electricity or electrical engineering. Sadly I was struck by no such inspiration this week, so I have something a bit different.
I went to college for a B.S. in Computer Science. The school I went to wasn’t an engineering school at all, so it lacked many science courses and departments. There was no electrical engineering department or course when I started there. Even the computer science department had weirdly forked off of the mathematics department some 20-25 years prior. There was barely a physics department when I started there. However, by the time I was a senior, they had started ramping up their STEM offerings and were trying out a one-time electrical engineering course with a new professor.
The biggest thing I remember about the course is that I should have taken it pass-fail. It wasn’t required for my major, and it was extremely hard. Being a new course they hadn’t really yet flushed out the difficulty level yet. Fortunately it didn’t knock me down too hard, and I learned some very interesting things while taking it.
One of the most interesting things I learned about was electrical network design. I would’ve actually liked to learn more about this, but the course was still under development, so I only got a small taste. In electrical network design, you learn about several laws and theorems.
The most basic way I can start to introduce the concept of electrical networks (circuits) to regular non-scientific people is by discussing two of the most basic layouts: series and parallel. Think about driving down a road. Say the road is just straight one-way road, with no side streets, no traffic lights, no stop signs…nothing. This is like a short circuit. You will be able to drive down the road unimpeded. Now imagine that the road has a series of traffic lights on it and you get a red light every time. To get down the entire road now, you’re going to have to pause at each light. You have no choice. The traffic lights on this road could be said to be in series with each other.
Now imagine that just before each light, there is a pull-off that takes you onto another road, parallel to the one you’re on. If you approach the light, and notice that it’s red, you can just pull onto the other road and continue on your way, basically unimpeded. The road that is parallel to the original road may also have lights on it, and you may or may not be able to avoid them as well by switching onto successive parallel roads. The traffic lights in this configuration are said to be in parallel. Assuming you want to get where you’re going as fast as possible, you’ll always choose to pull onto the parallel road if the light is red. You’re taking the “path of least resistance”. Electricity does the same thing.
Maybe you’re already one step ahead of me here, but there can even be parallel and series configurations on the exact same road network. Say you avoid one light by switching to the parallel road, but then you hit a series of two lights with no choice to switch to a parallel road. However, you’re able to see those two lights in advance, and you know if you stay on the main road, you’ll only need to go through one, so that’s what you do. Just like electricity, you will always take the path of least resistance.
Remember those old light strings where if one bulb burned out, the whole string wouldn’t work? That’s because the lights were wired in series. If you think about our road analogy, this would be the equivalent of a light that just always stays red. It wouldn’t matter if lights further down the road all turned green, you wouldn’t be able to move at all. Newer light strings connect the bulbs to the power in parallel, so if one bulb fails, the electricity can still get to all the other bulbs. On our road, you’d see that the red light wasn’t changing at all, but you’d be able to switch to the parallel road and continue on your way.
Of course, in actual electrical networks, series and parallel configurations are far more complex, but these two types of networks are the absolute bread and butter of any electrical system. I know this topic might not have been as exciting as others, but hopefully it was interesting nonetheless. I can’t always tell what will be interesting because what seems like a simple given to me might be very interesting to people who’ve never studied these things.