I am still not a physicist. It is my understanding that electricity works by sending electrons zooming down the power line after having been generated by a spinning turbine, moved by heat exchange or whatever. Well, where is the supply of electrons by the generator that are going to be energized? Where do they come from? Or do I have it all wrong?
They send out electrons, and they get electrons back. Electrons themselves are nothing special-- There are electrons all over the place, in everything. What’s special is for the electrons to be moving. Power plants cause electrons to move.
Yes, the electrons don’t go very far, and they are shifting back and forth on the different wires. On average overall the plant isn’t gaining or losing electrons.
Generally, in electricity we speak of electrical circuits. It is a circuit because there’s a closed loop (or multiple loops). The electrons move around it. Not many things spit out electrons to send them far away, or vacuum them up. The few things that do might be thought of as specialty items in the realm of static electricity - for example, ion generating air blowers for dust removal.
Yes, there are electrons in every atom, of everything. Some of them, particularly in good conductors such as metals, are free to move from one atom to another. The power plant moves them.
For many purposes it is not too misleading to think of an electrical wire or cable as like a pipe full of water, and the power plant or battery or whatever as a pump, pumping it around. However, the pipe is not allowed to become empty, so in order to flow it must make a circuit, and come back to the pump again. It does not come out anywhere, but it can do useful work as it flows through some things, a bit like how we can get useful work out of water flowing through a water wheel. It is the energy in the flow (of both electrons and water) that is useful, not just the fact that they are there.
Like all analogies, of course, this one will break down if you try to push it to far.
The generator does not create electrons. Wires are already full of electrons, and its a convenient property of metals that there are a number of electrons that are not very tightly bound to any particular nucleus making a “sea” of loosely-bound electrons.
For an AC generator (as most “spinning turbine” generators are) you can think of the generator as making waves in this electron sea. Just like in ocean waves where the wave transmits energy without moving any of the actual water very far, the wave in the electron sea transmits energy down the wire without a net flow of electrons.
Actually, a local woman has discovered some special weight loss electrons that physicists don’t want you to know about.
They don’t come from anywhere; they’re already there in all the wires. What generators do is push the electrons back and forth so they can do stuff.
A “weird trick”?
It might be better to think of the wires coming from the generating plant not as a pipe full of water, but more like a bicycle chain. The generator “turns the gear” at one end, and the “gear” at the other end moves immediately, even though the links near the generator haven’t moved very far.
The electrons in the wire don’t actually move from one end of the wire to the other - they just vibrate back and forth, over a very short distance.
So, Electron A is sitting, more less, in a wire, physically, near the turbine. Does Electron A ever move down the wire and wind up in your lamp or whatever?
That’s definitely part of the “water in a pipe” analogy, with which I have no problem when used to generalize about voltage.
Yes, that’s what I hear.
These electrons also whiten your teeth, apparently.
If we were using DC, then yes, eventually. But we’re using AC, so no. Electron A moves a bit down the wire, then is pulled back, then moves down, then is pulled back, and never moves closer to your lamp.
Not an engineer, but this is my understanding. There is no “flow” to speak of. As the generator creates a negative potential, it forces electrons in the connected circuit away from the generator. As the generator then moves to the positive potential portion of the cycle it pulls those same electrons toward the generator.
It does this roughly 60 times or cycles per second in US generating plants.
What makes something like copper a good conductor is loosely bound valence electrons than can easily be pushed and pulled through the metal’s matrix with little resistance. Valence electrons are those in the outer most orbital.
Only if it is AC. With DC there is a real, continual flow, and most of our electronic devices, and anything running on a battery, run on DC. Even with AC, if you insist in introducing that complication into your explanation, it is easy enough to think of the water being pumped back and forth a little way in alternation. Remember, I said it was crucial to understand the pipe as being always full, a closed system, a circuit. It is not about the water getting somewhere, and coming out the other end (it doesn’t come out), it is about it being in motion.
I really do think the water analogy is both clearer and more accurate than your bicycle chain. It does not imply that any bit of water has to flow all the way from the pump to the water-wheel (or whatever) in order to do work there. Because the pipe is always full the distant water will get pushed over the wheel long before any of the actual water molecules that just came through the pump get there (if they ever do). It is much the same with electrons flowing through a wire, and we do actually talk of electrons flowing, just as we talk about current, another water-derived metaphor. There are no bike-chain metaphors in the language of electrical science, and for good reason, I think.
Another good analogy is imagine a tube full of marbles. The generator doesn’t create the marbles, it just pushes them. As soon as you push one marble, all of the marbles in the tube move almost simultaneously, so the motion propagates through the tube very quickly even though the individual marbles don’t move much at all.
Modern power systems are AC, which means the marbles go in one direction for a bit then switch and go in the other direction for a bit. You can harness the energy from the moving marbles but the actual marbles don’t go anywhere they just go back and forth a bit.
Okay, follow up. Thanks for the replies that are, har har, enlightening. The electrons at the power plant do not come to my house? Is that right? It’s like a chain reaction where they are exciting the ones nearest them that then do the same further down the line?
It seems to me that introducing these issues about about AC is just going to confuse and obfuscate any attempt to answer the OP’s very basic question. Sure, actual present day power grids use AC generators, but they don’t have to (as Edison showed), and anyway, you can’t really understand AC unless you understand DC, and basic issues about current flow (which is what the OP asked about) first.
Yes, but that is not really the issue. Things could be set so the actual electrons pushed out of the generator actually do arrive at your house (although your electrical stuff would start working before they got there, because the electrons in the wire would already have been "pushed into motion by the “pressure” coming down the wire). There are some technical reasons why it is more convenient to use the back-and-fort flowing AC (Alternating Current) system for most long distance power transmission, rather that the DC system (Direct Current, where the electrons continually flow in the same direction) but they do not have much to do with your original question. In either case, though, it is the fact that the electrons in the wire are in motion that allows them to do useful work.
Your understanding of electricity if flawed. Don’t worry, nearly everyone’s understanding of electricity if flawed (including my own). Electricity is strange stuff. You can’t see it, smell it, or weight it. You can only see how it affects other things and come up with explanations on what is going on.
This is where all the analogies come in. You can understand water in a hose, so if you think of electricity as water flowing in a hose, you can understand some aspects. Same with the bicycle chain.
But, electricity is not just electrons. Its moving electrons. You can have a jar full of electrons and it won’t do squat, just sit there and not bother anybody. Until you get them to move.
OK, you ask, what about static electricity? I’ve been zapped pretty bad from static electricity.
Well, technically, the static electricity didn’t do squat (or only squats, I am not sure; my point is that static charge doesn’t do anything but sit there). Static electricity discharge, however, can be a bitch. If a static charge is large enough over a local area, it can rip electrons away (or force electrons on) the non-conducting material surrounding the static charge, allowing it to conduct electricity (moving electrons), Those moving electrons is what zapps you, not the ones sitting still.
The reasons the analogies fail is that electricity concerns two forces, not just one, namely electric charge and magnetism. These two forces are related, but notably different. In electrical devices, it is the magnetism that does the work. The magnetism resulting from the moving electrons. This is true whether it’s AC or DC. You see, it is not that the generating plant makes the electrons move (electrons are moving all the time), but is is that it gets them to move in concert with the other electrons as a result of a moving magnetic field. The electrons propagates this field down the conductor, and it is the filed at the other end that does the work. Now, in order to be able to propagate the field, you have to have a complete circuit, which is where the water hose analogy come in.
Like I said, electricity is strange stuff. Frankly, am amazed that a creature that exhibits such monumental stupidity as homo sapiens figured out as much about it as we have.
excavating (for a mind)
It gets even stranger. Electrons and holes (places in a matrix or orbital that can accommodate an electron) can be strongly bound to create virtual particles called polaritons and recently a new type of laser based on the principle has been developed.