How does AC electricity travel anywhere if it is going “back and forth”?
In: Engineering
It doesn’t go anywhere. It does just go back and forth.
That going back and forth is still able to do work if you have the right machine to harness it, like an electric motor, or a heating element.
Think of a device like a Newton’s Cradle (https://en.wikipedia.org/wiki/Newton%27s_cradle) and assuming all the balls are still. If you push on the end of one ball, all the balls move in the same direction, and if you push on the other end, they move in the other direction. That’s basically how AC current works: all the electrons are moving back and forth.
Imagine a tube filled with balls.
I can push the balls back and forth and they will move at the other end even though I’m not there.
That’s a cable. The balls are charges in the cable.
If I make a loop with the tube, so that when I push the balls inside the tube, they will move around the loop, that’s a circuit.
When I apply a voltage the balls are pushed. At the other end, the balls impart a force… that’s how we make electricity do things at the other end of a cable.
It doesn’t matter if I keep pushing the balls in the same direction, or if I push them one way and then the other way. The other end still has balls moving past it that are imparting energy through their movement. With a little inventiveness, I can use that energy to do other things, no matter which way the balls move, or if the direction of the balls changes 50/60 times a second.
AC electricity does not really travel anywhere. It is more like a force at one end of a long stick that pushes the opposite end. It moves electrons at one end of a wire and that causes electrons to move at the opposite end. Because the entire wire is chock full of electrons. Each electron going in the wire has to force an electron out the opposite end.
AC electricity is like the pistons and connecting rod on a steam locomotive. The pistons move back and forth, pushing out then pulling back. You can turn this into rotation by pushing a wheel on one side, then pulling on the other.
The piston doesn’t have to travel to the wheels, just the force.
Imagine a never-ending “heave-ho” game of Tug-of-War (with an impossibly-long impossibly-stiff impossibly-light impossibly-strong rod instead of a rope).
One team pulls it a foot to the left, then the other team pulls it back a foot to the right, then the other team pulls it back to the left, then to the right, and so on and so forth, ceaselessly.
If that impossibly-long rod passes by your house, it’ll still be “heave-ho”-ing a-foot-to-the-left, foot-to-the-right, foot-to-the-left, foot-to-the-right, etc. even if you’re miles away from the competitors themselves. You could totally find a way to attach a saw or a butter-churn or *something* to get some useful work outta that movement even if that tiny “section of rod” in your yard never actually leaves the yard.
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