Question: How do electronics work

Ciarán O'Brien answered on 8 Nov 2014:

Electronics are a very clever result of people figuring out what electricity really is and how it behaves. Everything is made up of molecules, right? And all those molecules are made of different atoms of the various elements. Those atoms are all made of a combination of subatomic particles called protons, neutrons and electrons, which each have different electrical charges (the reason for this is really complicated and has to do with the direction these particles spin). We didn’t always know that electricity was the result of electrons following the easiest path they could from where they’re densely packed to where they’re not.

Once we learned that, we were able to construct clever little obstacle courses where we put electricity in one end, and made it do things for us on the way through. That’s all an electronic circuit is, really; It’s a network of pipes that electricity flows down, and we put little gates and switches in the way that alter which pipe it flows through, or how much flows through a given pipoe, or whether if flows through a pipe containing a switch that closes off one pipe and opens another for it to flow through.

Some materials allow electrons through more easily than others, but metals are especially good at it which is why electronic circuits use metal wires. You can put in a resistor (electricity flows less easily through those) into the wire to make less electricity flow down that one wire, or you can add in a transistor, which is like a resistor but you can alter how much or little electricity it blocks by using another circuit. Transistors act like a switch that can turn the flow on or off along a wire, and they’re the reason we can actually make electronics.

I like to think of electronic devices as really tiny Rube Goldberg machines. The band OK Go made a really nice one for one of their videos (note for teachers- that’s red paint, no need to feel faint): https://www.youtube.com/watch?v=qybUFnY7Y8w

Think of the electricity as the little balls and dominos rolling and toppling, they’re just following the path of least resistance (in this case it’s gravity pulling them down, but in an electric circuit it would be the difference between positive and negative charges pushing the electrons along). And all the levers, glasses and other things they hit off to start another ball rolling or domino falling are the transistors we put in their way, which are off until the electricity hits it, and it starts another circuit moving. By carefully deciding where to put a transistor, we can make the electricity do interesting things, like spelling out a name like Ciarán on this screen by only lighting up the bits of the screen that make that shape.

Electronic circuits are way, way smaller than the “circuit” in that OK Go video though, a computer contains billions of transistors on its microchips, only nanometres apart, which makes them insanely fast at switching on and off, and lets us make some very, VERY complicated obstacle courses for them that produce useful effects. For example, they can control an electromagnet in your headphones to vibrate at different frequencies to create soundwaves, or control which bits of a screen light up in a specific colour, so we could make a piece of the screen that looks like an Italian plumber eat a mushroom and jump down another piece of the screen that looks like a pipe. Or a blue hedgehog, if you’re not a Nintendo person.