How does AC(Alternating Current) work?


Till what I know, AC alternates between positive and negative. How does that to make a flow? How do you connect a postivie and negative if it’s always changing?

In: 6

Pretty sure AC is the high current inside the high voltage lines. It’s pulled and pushed through the lines. Like first pulled back to the plant, then pushed back out to be used.

I’m still learning this, in not oo sure

Imagine you want to transmit “work” aka “energy” across a distance. You could use a long pole for example and push that pole from the source to the destination but eventually you run out of pole, right? This is something like what happens with a battery, the energy is transmitted by pushing electrons in one direction only.

You could do something else. You could push the pole then switch to pulling, then pushing then pulling. Consider this movement is what one of your legs might do when peddling a bicycle.

Depending on what you want to do with the energy you might need to translate it from that back and forth form to something else and this is what a “transformer” does. Your phone charger is an example of a transformer.

AC has a live and neutral wire. The live wire alternates between positive and negative, and the neutral remains at zero. During the negative phase, the live wire forces electrons out, through your machine, and into the neutral wire. During the positive phase, it sucks them back. In both cases, a force pushes the electrons through the machine, and so in both cases their movement can be dammed and used to do useful work.

The physical way to make an AC current is to use DC to power a spinning rotor with electromagnets on the ends, causing the magnetic field to spin. If you recapture that magnetic field back to electricity through a line crossing on one axis only, you end up with a back-and-forth charge in the shape of a sine wave. Your output is AC.

Edit: Modern transformers have pretty rad designs that don’t need moving parts, but I find imagining something mechanical easiest to visualize.

Think of AC current like cutting a tree with a two-man saw, the motion is back-and-forth. DC current is more like a chain saw. Both motions can get work done.