eli5 What’s the difference between AC and DC currents?
In: Engineering
DC has a stablished polarization, a battery has a + and a -, if you get those poles reversed it won’t work.
AC constantly changes if it is + or –
DC (direct current) is always in the same direction. It’s like you have a pipe full of marbles, and you tilt it so the marbles all go running the same way. (The pipe is a wire, and the marbles are electrons.)
AC (alternating current) keeps reversing direction. That’s like you have a pipe, and you rock it back and forth so all the marbles run to the left, and then they stop and run back to the right, then back left, and so on. In theory with an isolated AC lightbulb the same electron could run back and forth through the bulb thousands of times.
Mushroomfields makes a good point – batteries deliver DC, and generators produce AC. (You can convert AC into DC, using a device called a rectifier, and you can turn DC back into AC using an inverter.)
AC switches direction of the electron flow back and forward so there isn’t really a pre-decided + or – which is why it doesn’t matter which way you plug your electronics into a wall socket. If you google a “*sine wave”* you can see how the amplitude switches back and forth from the + and the –
DC however means that the electrons only flow in one direction (from the – to the +) which means that plugging your electronics in the wrong way can result in serious problems. (although most electronics have lots of safety measures nowadays)
AC is generally used in “larger” contexts where more power is involved, such as for large motors, electricity generation and distribution as it functions better in the purpose as transporting power through DC would be terribly inefficient among other things.
DC however works great for small circuits where you may want to apply logic components such as transistors, diodes and controllers. This is why your laptop has that little box that transforms the power from AC into DC where it runs into your battery and computer.
DC is pulling a rope tied to the bucket in the well. In order to get the bucket of water, you need to pull the entire length of rope.
AC is using a ratchet to pull the bucket. You move the rarchet back and forth to pull the bucket of water out of the well.
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