Electrons - when they move from Atom to Atom - where do they end up?

[T.M.Haja Sahib]

Completing the circuit with a voltage across it causes a dispersion of surface charges at near light speed that position themselves in a shell along the wire.

This can not be correct.

You forgot Einstein.

The mass of a physical object including electron tends to become infinitely large, as it approaches the speed of light.

 

[mivey]

You mean magnetic energy (and no electric energy) ?

I mean the energy we are delivering to the light bulb at the other end.

Don't you think kinetic energy associated with moving electrons as ''energy''?

Of course. But the kinetic energy is a mere fraction of energy as compared to what we deliver to the bulb plus the electrons do not stop when they reach the bulb. You will have energy losses in the conductor but that is not because the energy we are delivering is being carried inside the wire core.

 

[mivey]

This can not be correct.

You forgot Einstein.

The mass of a physical object including electron tends to become infinitely large, as it approaches the speed of light.

Call it 60-80% c if it makes you happy but that is a lot nearer light speed than ~0.00000000002c that we have with the electrons moving in the wire.

FWIW, we routinely have particles exceeding light speed (but not the light speed in a vacuum) in the water surrounding reactor cores. That is what creates the blue light in the water. But that is completely off topic.

 

[T.M.Haja Sahib]

You will have energy losses in the conductor but that is not because the energy we are delivering is being carried inside the wire core.

If the energy is not travelling inside the conductor but outside, the change of energy to thermal energy must also originate outside the conductor or at least at the surface of the conductor. But is it not the inside temperature of the conductor greater than the surface temperature?

 

[mivey]

If the energy is not travelling inside the conductor but outside, the change of energy to thermal energy must also originate outside the conductor or at least at the surface of the conductor. But is it not the inside temperature of the conductor greater than the surface temperature?

I would have to dig out my physics book but as I recall, there is an energy vector parallel (?) to the wire and that is what travels to the load. There is also an perpendicular (?) energy vector that causes the parasitic heat loss.

It may be just an over-simplified means of remembering the big picture and I would have to verify that, but that is the picture that sticks in my mind. Not too different than what happens when the energy reaches the light bulb and becomes light/heat. After all, the wire resistance is really a parasitic load along the delivery path.

At any rate, the energy travels in the field surrounding the wire. There was at least a good chapter or good portion of a chapter covering the physics and why the energy was not traveling inside the wire.

Add: I do not recall anything about the core vs surface temperature and/or any transient vs steady-state differences.

 

[mike_kilroy]

I am thrilled with your descriptions Mivey and will be researching this more myself - thank you for such definitive descriptions of facts that I never learned in engring school years ago.

what would you say about the energy in a lightning bolt since there is no wire?

 

[Phil Corso]

Mivey... I believe you are referring to the Poynting Vector!

Regards, Phil Corso

 

[steve066]

Energy does not travel in the wire with the charges but travels outside the wire in the surrounding field.

I'll agree with that. That's what they always said in school, but I never really understood it. If you can't have the E&M fields without the moving electrons, and you can't have the moving electrons without the E&M fields, it seems kind of arbitary which carries the energy.

But I accepted what my professors said, mostly on faith (and because I liked to get test answers right ).

At room temperature, the thermal motions of the free electrons is larger than the motion cased by an applied electric field. This is a random motion (basically noise) and the electrons are going all different directions.

When an electric field is applied, the electrons generally tend to move in the direction of the applied field. There is a general "electron drift". That's the textbook term they used back when I was in school.

But due to the thermal motion being larger than the "drift" of an individual electron, many of the electrons will still be traveling backwards, and many are going perpendicular to the wire.

 

[steve066]

I didn't say it contradicts what happens in a wire... I said it contradicts "bump theory". I am of the belief that electrons do not bump into each other like billiards (unless they are part of a super-collider experiment). Having like charges, as they approach another, they repel each other.

Electrons are very small, so I don't think they bump into each other. They do bump into atoms. An electron will start to accelerate in the direction of the applied field, but then it will hit an atom and bounce back the direction it came from. then it does the whole process over again. That's why the net motion of a single electron is very small.

 

[mivey]

I am thrilled with your descriptions Mivey and will be researching this more myself - thank you for such definitive descriptions of facts that I never learned in engring school years ago.

You are welcome. School gives you a toolbox of basic engineering knowledge that you can use to continue learning and I have learned much since graduation.

what would you say about the energy in a lightning bolt since there is no wire?

The plasma acts as the conductor. I'm no plasma physics expert but I would say that the energy still travels in the fields. However, most of the energy gets lost along the way to the finish line in heat, light, thunder, radio emissions, etc.

 

[mivey]

Mivey... I believe you are referring to the Poynting Vector!

Regards, Phil Corso

That would be correct and is used in conjunction with the surface charge model.

 

[mivey]

I'll agree with that. That's what they always said in school, but I never really understood it. If you can't have the E&M fields without the moving electrons, and you can't have the moving electrons without the E&M fields, it seems kind of arbitary which carries the energy.

But I accepted what my professors said, mostly on faith (and because I liked to get test answers right ).

Let me give you some food for thought from a post in a different thread that extends beyond faith:

What causes EMF problems if the energy is contained in the wires? Why does the EMF problem decrease as the wires are brought together?

What causes inductive heating if the energy is contained in the wire? Why does keeping the wires together fix this problem?

Electrons do not jump the gap in a capacitor neither do they jump the gap in a transformer, but the energy still gets through.

If an electron is carrying energy to the load as it flows from the source to the load, then a different electron would take energy from the load as it flows from the load to the source and the load would get a net zero delivery of energy.

 

[T.M.Haja Sahib]

But, mivey, this seems nonsense: asserting that energy to light up a bulb, for example, travels outside the connecting wires. For the energy to light up the bulb is contained in the potential energy of moving electrons in the connecting wires. Electrons on the one terminal of the bulb will be at a higher potential and the electrons on the other terminal at lower potential; the difference between the two gives the energy expended in the filament of the bulb per electron per unit time.

 

[ggunn]

This can not be correct.

You forgot Einstein.

The mass of a physical object including electron tends to become infinitely large, as it approaches the speed of light.

The individual electrons do not move anywhere near that fast, just the electric impulse. It's analgous to a sound wave moving in air; sound travels at about 1180 feet per second in air at sea level, but that doesn't mean that a sound source generates wind of that speed. That's a good thing, right?

 

[Besoeker]

The individual electrons do not move anywhere near that fast

A obese chain smoking snail would make them look positively pedestrian!
Their negative charge isn't a charge in the sense of The Light Brigade.

 

[pfalcon]

1> Electrons are particles. (Most common at this time)
so electrons carry the charge in the appropriate direction, bump into another electron and pass the charge.

2> Electrons are charges extended in space. (Einstein's favorite I believe)
so electrons rub elbows and transmit the charge like a bucket brigade.

Electrons are matter with a negative charge. They do not pass their charge to another electron. Electrons also demonstrate characteristics of waves.

Einstein died trying to prove this stuff so it's not settled physics yet.
Per Einstein: All matter is dense energy that is spatially extended as a field.
But he never created the Unified Field Theorem he was after so even his conclusions are suspect.
Photons have been demonstrated as a charge passing from electron to electron (particle behavior) and exhibit fringe effects (wave behavior).
Einstein knew this and declared that particles have no rightful existence in our universe.

3> Electrons are standing waves. (A new one)
so electrons get juiced up, couple resonantly with the next in line, and pass the energy.

As is all matter, since it is all really energy in some bound state (according to theory). Exactly how it is bound to make matter is not known but it is certainly interesting reading the theories.

Standing waves are a new theory not widely accepted yet. Einstein's spatially extended fields are the most common; Particle theory is dying out. And it is indeed fascinating.

In any event, the electrons don't actually seem to go anywhere, the different theories all come back to:
Receive energy (boosting the orbit?)
Connect to another electron (bump? resonate? arc?)
Deplete energy (reducing the orbit?)

Energy does not travel in the wire with the charges but travels outside the wire in the surrounding field. The electrons are not getting an "injection" of energy juice and then passing it to their neighbor.

Presumptious since there's not a physicist who can prove that. Again, Einstein died not knowing.
The leading theory right now is actually that the electrons never really travel far from where they start. Instead they DO pass energy along. Per Einstein this is done by bumping fields which are spatially extended from the electron center (not a particle per Einstein). And that the magnetic field is part of the electron's spatially extended field.

As such, the electromagnetic fields are part of the spatially extended field of the electron. Energy transfer occurs within the conductor, Mechanical transfer occurs in the surrounding field, Energy-Mechanical exchange is linked by conversion through the electron.

But hey, you could have it right. I mean, Einstein said he didn't know. Newton said he didn't know. All the top physicists have said they don't know. Maxwell's equations resolve to a black hole at the center of every piece of matter in the universe including the center of electrons. They apply a "normalizing" equation to eliminate the near zero radius impossibility called a black hole because experimentation shows the equations are wrong near zero radius. But though Maxwell's equations are proven to be flawed (in earthly particles) some really smart people still believe they exist out in space by using Maxwell's equations. Go figure.

So, not actually disagreeing. Just pointing out that the best of the best in physics don't agree yet.

Electrons are very small, so I don't think they bump into each other. They do bump into atoms. An electron will start to accelerate in the direction of the applied field, but then it will hit an atom and bounce back the direction it came from. then it does the whole process over again. That's why the net motion of a single electron is very small.

Contemporary theory holds that electrons aren't really that small. Mainly because contemporary theory says they are either Fields (per Einstein) or Standing Waves (per Wolff). This resolves Newton's problem of matter acting at a distance without any means of communicating. Their fields interact (bump), and there is no actual particle at the center.

The partical effect is caused by energy transfer between matter. The wave effect is created because matter is spacially extended. Maybe. :dunce: We don't really know.

 

[pfalcon]

Copper has 29 electrons and one valence electron. When a free electron(1) knocks the valence electron(2) free from it's orbit (bump theory), the electron(1) transfers it's energy to the second electron(2). The first electron settles into orbit, making the second electron the free electron. Electrons are never depleted, they are replaced.

Think billiard balls for energy transfer.

Another question... where does the very first free electron come from when electricity is produced by a generator? If all the electrons in a dead wire are neutral, what is the very first thing that happens to make electricity? A free electron has to come from somewhere, where and how is it "stripped" from another copper atom to start the process of energy transfer?

Alternate theory says the valence electron never actually roams free but rather gains excitation. Since electrons are fields (contemporary theory) rather than particles they can interact at a distance (bump). This is much more like the swinging ball toy called "Newton's Cradle".

 

[mivey]

The individual electrons do not move anywhere near that fast, just the electric impulse.

That's correct. They don't have to move very far to create a charge gradient around the entire circuit because each little electron makes its own contribution.

 

[mivey]

Einstein died trying to prove this stuff so it's not settled physics yet.

It's true we do not have a snapshot of what is going on down at that level but we do make models based on observed behavior. That's what all the pointy-heads are doing at places like the Fermi lab.

The leading theory right now is actually that the electrons never really travel far from where they start. Instead they DO pass energy along. Per Einstein this is done by bumping fields which are spatially extended from the electron center (not a particle per Einstein). And that the magnetic field is part of the electron's spatially extended field.

That may or may not be true but even so the extended field is not contained in the metal.

But hey, you could have it right. I mean, Einstein said he didn't know. Newton said he didn't know. All the top physicists have said they don't know. Maxwell's equations resolve to a black hole at the center of every piece of matter in the universe including the center of electrons. They apply a "normalizing" equation to eliminate the near zero radius impossibility called a black hole because experimentation shows the equations are wrong near zero radius. But though Maxwell's equations are proven to be flawed (in earthly particles) some really smart people still believe they exist out in space by using Maxwell's equations. Go figure.

So, not actually disagreeing. Just pointing out that the best of the best in physics don't agree yet.

Since none of us have made the "Fantastic Voyage" down to the atomic level to take a look, not to mention we can't see the "invisible" realm of fields and such, it is still called "theory". I wish I could see 100 years into the future as I like seeing how stuff works.

For now, I still buy into the field theory version as discussed in "Grounding and Shielding In Facilities", Morrison/Lewis, 1990, pg 15

1.8 Field Concepts
All electrical energy is transported by electric and magnetic fields...Conductors do not carry energy-they simply direct where the
energy can travel. The idea that conductors carry power is a common misconception.

I would suggest buying a copy as it is a nice reference and not a hard read. You can also read more from the author here:
http://www.ralphmorrison.com/Ralph_Morrison/Moving_Electrical_Energy.html

 

[mivey]

and will be researching this more myself

Here are some references for you:

"Energy transfer in electrical circuits: A qualitative account":
http://stc.huji.ac.il//staff_h/Igal/Research Articles/Pointing-AJP.pdf

"A unified treatment of electrostatics and circuits":
http://matterandinteractions.org/Content/Articles/circuit.pdf

"Surface charges and fields of simple circuits":
http://galaxy.cofc.edu/pubs/AJP01002.pdf

Please refer to the footnoted references as well as there are many good ones and I don't feel like making a list of the ones I have collected over the years. I would suggest getting a copy of the physics text "Matter & Interactions" by Chabay/Sherwood as it is an excellent reference.