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Why is it not possible to make a device operate by forcibly putting electrons into the system, closing the loop, and having electron repulsion do the job of making charge flow?

Making electrons flow is what creates electricity. So if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together. This would cause charge to flow around and create electricity.

What am I not taking into account here?

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    \$\begingroup\$ What is Conductance and capacitance? \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Aug 24 at 7:41
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    \$\begingroup\$ run water into a hose, then quickly connect the hose in a loop and watch the water keep flowing through it without any force to keep it moving... \$\endgroup\$ – old_timer Aug 24 at 9:50
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    \$\begingroup\$ roll a ball down a hill onto a flat road and watch it roll forever on that flat/level road. \$\endgroup\$ – old_timer Aug 24 at 9:52
  • \$\begingroup\$ Supposedly as you approach zero kelvin this is possible. Heard it in class one day from the professor, never followed up on it. Of course it is probably not possible to view/measure this to see that it is working as that would stop it from working. Perpetual machines dont work is the short answer. \$\endgroup\$ – old_timer Aug 24 at 10:00
  • \$\begingroup\$ This sounds to me like a battery or capacitor. In the most layman terms (I'm not a scientist): electrons are trapped in a way that they're trying to escape the (-) terminal, and when connected to a ground they'll flow out a little, and when connected to the absence of electrons on the (+) terminal, they'll flow out a lot. I mean, what you're describing sounds a lot like a Leyden jar— an early form of capacitor used for electricity experimentation in the 1700s. \$\endgroup\$ – Slipp D. Thompson Aug 25 at 17:44
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Making electrons flow is what creates electricity. So if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together. This would cause charge to flow around and create electricity.

You're getting lot's of things wrong here.

  1. The term "electricity" is extremely vague and not technical at all. There is no physical phenomenon called "electricity" nor any physical quantity called like that.

That term is a relic from the past when people didn't know much about current, voltage and other macroscopic electrical quantities. Let alone electromagnetic theory. That term can be used correctly only in non-technical/scientific contexts or only in the vaguest of sense. In other words: you don't measure "electricity", you measure a bunch of well-defined physical quantities related to electrical phenomena.

From a technical point of view, what you call "electricity" in the sense of "some kind of energy that allows us to do stuff" is called "electrical energy" or "electrical power".

  1. Electrons moving around don't necessarily generate electrical power. Even assuming electrons were classical particles (and not some elementary quantum particles with all kinds of odd, non-intuitive behavior), a flow of electrons would constitute an electrical current (or a current density distribution, if the body wasn't a thread-like body).

Currents can generate power only if they flow through a system that is able to draw energy from them. The electrons have to lose energy to provide power to the "outside world". In other words, they must travel across some sort of potential barrier. In technical terms, if the electrons moving from point A to point B are to generate power, there must be a voltage across those two points (point A must be at a lower voltage than point B, in particular).

  1. For electrons to "bounce around" without having "nowhere to go", you must put them in a body that is both an electrical conductor and that is insulated from the rest of the world. (If the body weren't a conductor, electrons wouldn't be able to "move around", they would stay "locked" to the atoms of the body).

In this scenario electrons, even if moving, wouldn't be able to generate power, because any point of a perfect conductor is at the same potential. So there is no voltage drop, hence no power.

Of course I have neglected lots of additional problems that arise when you consider the true nature of electrons, which are not tiny weeny balls of matter, but quantum particles to which classical reasoning cannot be applied coherently.

BTW, it has already been hinted to by others in this thread that you can have a continuous flow of current in a ring-shaped superconductor body. The electrical resistance is virtually 0 and the electrons don't lose energy while moving (ideally). There have been experiments in which such a "circular current" has been maintained for days (IIRC) without further external energy provision.

  1. Conservation of energy. Moving electrons (i.e. electrical currents) don't generate power (energy) out of nowhere. They are just a convenient carrier for power (energy) generated elsewhere. There are machines called electrical generators (batteries, alternators, photovoltaic generators, etc.) that take energy from another source (chemical, mechanical, electromagnetic, etc.) and turn that energy into electrical energy by putting electrons in motions. Then electrons are just, as I said, convenient carriers, since they can easily travel in wires to power up electrical loads placed even kilometers away from the source of power.

Remember: energy in nature cannot be created. It can only be transformed from a form into another. This is called the Energy Conservation Law and it's a basic principle of the Universe that no validated scientific experiment has ever been able to disprove.

Any time anyone has "witnessed" phenomena that violated that conservation principle, it has been established by scientific analysis that the phenomena were observed without taking correct measurement into account or that some other experimental mistake has been made (assuming there wasn't bad faith and the phenomena were not part of a scam).

Truly scientifically proving that the Energy Conservation Law is not universally valid would be a discovery worth a couple of Nobel prizes!

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What am I not taking into account here?

That is in effect what a voltage source does: It force electrons through a system if there is a closed loop.

Or going to a more abstract layer: You need energy to force electrons through a system. In effect you are using energy to generate electrical energy. It all comes back to the law of conservation of energy.

if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together.

What you describe is more like static electricity. We can pump a lot of electrons in an object and then isolate it. The electrons may move around a lot but that does not create energy.

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This is exactly like saying why can't I create water pressure if I just start the water flowing in pipes and then connect them into a circle. The water will flow but eventually the resistance in the pipes will slow the water down to a stop. Same thing with regular wires, the voltage will be lost.

However, if you use a superconductor, the electrons will circle forever. But it won't give you more energy, only allow you to store it.

What you are not taking into account is the resistance and the loss of the system. There are no ways to classically create or destroy energy, only convert it or store it.

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  • \$\begingroup\$ No, it's exactly like saying “why can't I create water pressure if I just start high-pressure (‘forcibly putting electrons into the system’) water flowing in pipes and then connect them into a circle”. You'll have a discharge when you connect the pipe-loop up to a lower-pressure space (ground), but you won't have continual flow around the pipes beyond initial equilibrium balancing. \$\endgroup\$ – Slipp D. Thompson Aug 25 at 17:46
  • \$\begingroup\$ @slip What about momentum? The water isn't going to instantly stop the instant the loop is made \$\endgroup\$ – Voltage Spike Aug 26 at 5:02
  • \$\begingroup\$ On a scientific level, true, that too. On a realistic level, water tends to have high friction and comes to a stop really quick. The time it takes to shut off your high-pressure input isn't too much shorter than the time the water would take to stop flowing. \$\endgroup\$ – Slipp D. Thompson Aug 26 at 5:05
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Why is it not possible to make a device operate by forcibly putting electrons into the system, closing the loop, and having electron repulsion do the job of making charge flow?

You have just created a charged body, the charge will distribute based on the geometry of the object and then stop. No more current. You've got static.

enter image description here

Figure 1. When an object is charged the charges do not always spread equally over its surface. With a round shape they are evenly spread but with a pointed shape the charges are always concentrated around the point. Source: School Physics

So if we are able to put electrons into a system, close the loop so the electrons have no where to go, then the electrons would be constantly bouncing around together. This would cause charge to flow around and create electricity.

No it wouldn't. Electrons are moving all the time anyway but their average movement is zero.

See @wbeaty's answer to Is the direction of an electric field opposite to the direction of a current? which may help clarify your thinking.

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We have a device that does this, I suppose: A Van de Graaff generator. You may have seen one before:

enter image description here

Perhaps what you are missing is a rigorous definition of what you mean by "electricity". In most electrical devices (like toasters, cell phones, and elevators) we use mobile electrons (in metals like copper and metalloids like silicon) as a sort of "fluid" to perform work at a distance. It is not unlike a closed hydraulic system.

Putting an excess (or deficit) of electrons in a body simply makes a charged body, like the woman in the above picture. The repulsion between like charges can do some interesting things, like make one's hair stand on end. But since they've nowhere to go, no work is performed.

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