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

[mivey]

The authors assumed in their paper that charges reside only in the surface of the conductor with no resistance.

Surely when a charge is given to a conductor with resistance or no resistance, it resides only on its surface.

But when the conductor is forming part of a circuit and conducting a current, charge is everywhere in it.

Even when a superconductor is conducting current, charge is everywhere in it.

What charges do you mean? Of course there are charges everywhere. The makeup of atoms includes positive and negative charges.

So the horizontal component of electric field inside a conductor can not be ignored even when the conductor has no resistance and so energy flows also inside the conductor during conduction of an electric current.

Energy is being dissipated in the conductor's parasitic load. This is not the energy that is traveling to the load at the end. In case you missed the prior posts or did not completely read the links:

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.
...
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.

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

 

[T.M.Haja Sahib]

What charges do you mean? Of course there are charges everywhere. The makeup of atoms includes positive and negative charges.

Energy is being dissipated in the conductor's parasitic load. This is not the energy that is traveling to the load at the end.

The authors assumed in their paper that surface charges cause current in a conductor.

But electrons making a current inside a conductor can move in a particular direction only when there is a component of electric field along that direction.

This field component exists inside the conductor irrespective of whether the conductor has resistance or not.

But the authors did not take into account this electric field component and energy associated with it and therein lies their error of assuming that the electromagnetic energy travels entirely outside the conductor with no resistance.

 

[mivey]

The authors assumed in their paper that surface charges cause current in a conductor.

But electrons making a current inside a conductor can move in a particular direction only when there is a component of electric field along that direction.

This field component exists inside the conductor irrespective of whether the conductor has resistance or not.

But the authors did not take into account this electric field component and energy associated with it and therein lies their error of assuming that the electromagnetic energy travels entirely outside the conductor with no resistance.

The axial electric field was not ignored. The axial field causes the current. The energy in the wire is heat loss and is not the energy traveling to the load. The traveling energy is outside the metal conductor. From Galili's and Goihbarg's paper:

The steady electric current in the resistive wire clearly implies an electric field of constant magnitude E2 inside the wire and collinear with it. This field is due to the distribution of surface charge established during the transient process.

Read the paper.

 

[T.M.Haja Sahib]

The axial electric field was not ignored. The axial field causes the current. The energy in the wire is heat loss and is not the energy traveling to the load. The traveling energy is outside the metal conductor.

What happens to the axial electric field inside the conductor, when the conductor is conducting a current and has no resistance?

It is nonsense to say it vanishes.

But the authors exactly do so by not taking into account the axial electric field, when they consider an ideal conductor i.e a conductor with no resistance in their paper.

 

[mivey]

What happens to the axial electric field inside the conductor, when the conductor is conducting a current and has no resistance?

It is nonsense to say it vanishes.

Of course it vanishes. If it did not vanish, you would get infinite current.

But the authors exactly do so by not taking into account the axial electric field, when they consider an ideal conductor i.e a conductor with no resistance in their paper.

They accounted for it. They just realize that it goes to zero as resistance goes to zero. A non-zero electric field in a superconductor would produce infinite current. Is that what you are now proposing?

 

[T.M.Haja Sahib]

Of course it vanishes. If it did not vanish, you would get infinite current.

You are correct. The axial electric field just vanishes inside a conductor with no resistance,

But still that the energy travels outside the conductor is unacceptable.

Prior to the energisation of the circuit, the electrons in the circuit conductors are at zero potential (with respect to ground) After energisation, they acquire a potential energy. This potential energy of the moving electrons is expended across the connected resistance of the circuit with ideal conductors.

 

[mivey]

But still that the energy travels outside the conductor is unacceptable.

That's OK. Physics is not for everybody and sometimes life is just easier with explanations that serve our purposes, even if they are not technically accurate. Sometimes simple is easier, maybe even better in some cases.

Prior to the energisation of the circuit, the electrons in the circuit conductors are at zero potential (with respect to ground) After energisation, they acquire a potential energy. This potential energy of the moving electrons is expended across the connected resistance of the circuit with ideal conductors.

Which ones get the energy, the ones on the positive side or the negative side or do they both get a heaping spoonful of the energy? Or do the ones on one side get a spoonful added and the ones on the other get a spoonful taken away? If the energy is contained in the conductor, how does this energy get across the gap in a capacitor or transformer? If the energy is contained in the conductor, how does a waveguide and an antenna work? If the energy is contained in the conductor, how am I able to walk under a HV line with a fluorescent tube in my hand and get the tube to light?

The fact remains that the energy travels in the EM waves. The energy traveling to the load is traveling in the EM wave outside the metal conductor. Science, physics, electronics, engineering (at least the electrical), etc. back that up. Whether or not it is acceptable to you is a choice you have to make.

 

[kwired]

I have been keeping silent because I really don't know enough to respond to the discussion. But after a little thought I have questions.

If energy travels around the concuctor rather than through it, why does resistance in the conductor reduce the amount of energy delivered? Why does this energy follow the path of the conductor? Why do we even need a conductor? There has to be something moving through the conductor. I always figured the field around a conductor carrying current was more of a by product.

At transformers we have a gap to jump. But if you had one turn on each side of the transformer not much energy would be passed on and in fact we would essentially short circuit the primary in most cases. We intensify the field by using multiple turns, this creates more inductance and reduces the amount of current in the primary so it doesn't have short circuit conditions anymore.

Just some things that don't quite make sense to me if (nearly all) the energy travels outside the conductor.

 

[T.M.Haja Sahib]

Further to what kwired stated:

The two authors did not derive a quantitative relationship for the energy traveling outside the conductors of the circuit, but only when applied to the resistance connected to the ideal conductors of the circuit. This makes the content of their paper more of an opinion than science based on numbers.

 

[steve66]

Mivey is right. The energy does travel in the EM wave. It is not carried in the electrons. I was taught this in school by professors who know a lot more about this than I do.

How else do you explain radio waves?

If energy travels around the concuctor rather than through it, why does resistance in the conductor reduce the amount of energy delivered? Why does this energy follow the path of the conductor? Why do we even need a conductor? There has to be something moving through the conductor.

A lot of this is answered by realizing the EM field follows the motion of the electrons, and is in direct proportion to the strength of the current flow.

I always figured the field around a conductor carrying current was more of a by product.

You can't have current flow without an EM field, so its kind of arbitray to say which is a product of the other.

A similar thing happens with voltage and current. Its tempting to say the current flow is produced by the voltage, but if you look at a resistor, the current flow through the resistor causes a voltage drop.

Its kind of like asking which comes first, the chicken or the egg. You can't have one without the other except in special cases.

 

[pfalcon]

Based on what source of information? Is this some mechanical engineering theory? The electronics and electrical engineering world know that the propagation rate is mostly based on the conductor spacing and the permittivity of what is in between. I'm sure most of the engineers and technicians on this site know that as well. And Einstein would agree also.

Based on that premise:
If you agree with what must be considered common knowledge about the significance of the permittivity of the stuff between conductors on the propagation rate (and what I would call generally unanimous agreement and knowledge about the propagation rate), the energy is flowing between the conductors.

From your sources:

However, the result of such an application and the resulting energy transfer in the circuit apparently did not satisfy Feynman. He wrote: ??this theory is obviously nuts, somehow energy flows from the battery to infinity and then back into the load, is really strange.??4 Feynman, however, did not persist and left the problem for others to find a reasonable explanation.

And this is the classic problem starting from back at Maxwell's four equation:

Dirac's quantum electrodynamics made predictions that were - more often than not - infinite and therefore unacceptable. A workaround known as renormalization was developed, but Dirac never accepted this. "I must say that I am very dissatisfied with the situation," he said in 1975, "because this so-called 'good theory' does involve neglecting infinities which appear in its equations, neglecting them in an arbitrary way. This is just not sensible mathematics. Sensible mathematics involves neglecting a quantity when it is small ? not neglecting it just because it is infinitely great and you do not want it!"

Equations such as the Poynting Vector stem from equations put forth by physicists like Maxwell and Dirac that use "Renormalizing" or as Dirac said: Ignore infinity in an arbitrary way. They mathematically describe the behavior of EMF and gravity under specific circumstances. And then someone tries to apply the equation outside those circumstances and gets wild theories. That's where things like black holes come from. Using Maxwell's equations for gravity "distant" from the wave center and apply it "at" the wave center then gravitic energy becomes infinite. Which experimentally has been disproven by testing electrons. According to the equation used to predict black holes in space, electrons have infinite energy at their center. But experimentally the energy is finite.

In your own article, Feynman called the theory you get when you extend the Poynting Vector outside it's limits as "nuts". Considering how much work he did with the Poynting Vector that's a pretty big condemnation. Not to the accuracy of the equations within their application; but a condemnation of the theory you get when you try to apply the equations outside their application.

Your "energy flow outside the wire" is largely based on using proximate wire equations and then theorizing that non-proximate wires must behave the same way. Feynman thought it was nuts and refused to pursue it. That while finding the equations to be accurate within their limited scope.

 

[mike_kilroy]

........A lot of this is answered by realizing the EM field follows the motion of the electrons, and is in direct proportion to the strength of the current flow.

Ah but it doesn't follow the motion of the electrons in the wire (maybe)!

According to one of Mivey's references, the electrons flow at a measly few INCHES PER SEC in the wire yet the EM field of course travels at the speed of lite down the outside of the wire...... I am slowly catching on but it sure is taking a while, especially with stuff like this to accept.... reading back over and over and over and over I am think I am coming away with the idea that the electrons in the wire are not actually moving from one end of the wire to the other but ony bumping around as mentioned by many others earlier and the voltage field applied across the wire sets them all in this SLOW motion of "/sec down the wire while the EM field actually carries the power....... whew.....

 

[pfalcon]

Mivey is right. The energy does travel in the EM wave. It is not carried in the electrons. I was taught this in school by professors who know a lot more about this than I do.
How else do you explain radio waves?
A lot of this is answered by realizing the EM field follows the motion of the electrons, and is in direct proportion to the strength of the current flow.
You can't have current flow without an EM field, so its kind of arbitray to say which is a product of the other.
A similar thing happens with voltage and current. Its tempting to say the current flow is produced by the voltage, but if you look at a resistor, the current flow through the resistor causes a voltage drop.
Its kind of like asking which comes first, the chicken or the egg. You can't have one without the other except in special cases.

Resonant coupling of what you consider particles passing energy would be one explanation for radio waves. There are several other theories. What you have to realize is that the wave equations for radio waves are built to describe those waves under specific conditions. They're not descriptions of the wave mechanics themselves. If they were then we'd have the Unified Field Theorem already - which we don't. The same is true for current/voltage equations. They're built to describe the behavior of electrical circuits under specific conditions.

Ah but it doesn't follow the motion of the electrons in the wire (maybe)!
According to one of Mivey's references, the electrons flow at a measly few INCHES PER SEC in the wire yet the EM field of course travels at the speed of lite down the outside of the wire...... I am slowly catching on but it sure is taking a while, especially with stuff like this to accept.... reading back over and over and over and over I am think I am coming away with the idea that the electrons in the wire are not actually moving from one end of the wire to the other but ony bumping around as mentioned by many others earlier and the voltage field applied across the wire sets them all in this SLOW motion of "/sec down the wire while the EM field actually carries the power....... whew.....

And yet, in Mivey's references his chief physicist reference says the basic theory is "nuts" while confirming the equations are accurate. Most of the physics discussions I've seen agree that the electrons only move in ionic fluids not solids. Therefore in the wire they only oscillate according to the sine wave - not move to the end. The "free" electrons oscillate between metallic particles being shared in a very limited area.

Remember that equations for conditions such as in coax cable are built to describe very specific conditions. Therefore things that may be physical, energetic, and significant to how the coax operates may very well cancel mathematically for the purpose of solving specific answers. Einstein described electrons as being fields within the conductor that are extended to affect things at a distance. With that description you can build complex equations that work only with the extended fields and neglect the electron entirely. And those equations are accurate for their designed purpose. Sort of like the blind man describing the large, slight rough, slightly yeilding wall in front of him; then the trainer leading the elephant away.

People are prone to take things like Maxwell's equations out of scope to build theories. Which is what Feynmann was getting to when he described the "out of scope" theory of energy coming from infinity that the Poynting Vector implied - as nuts.

 

[glene77is]

pFalcon,
Have read and agree with
"Dirac's quantum electrodynamics made predictions that were -
more often than not - infinite and therefore unacceptable."

Mivey,
As always, right on target.

Astounding thread of thought.

glene77is

 

[__dan]

Feyman modelled atomic structure as a spherical cavity resonator, regarding photon absorbtion and emission. His Lectures on Physics book set are some interesting reading. He was an independent thinker, asking why and what. His technical writing is very readable, accessable, which is rare in the field. Linus Pauling's work is also very readable and insightful.

A charge in motion radiates. This radiation is an emf field that acts at a distance (Faraday, Lenz, Maxwell). Charged matter also responds to the applied EMF, electric or magnetic field. Charges in motion follow the conductive path, bound by the wire and the insulating materials. The field follows the environment, it is in everything, everywhere. Field strength varies with the facts of construction and useage.

Applying voltage is an applied electric field. There are a variety of effects that happen simultaneously, free charges move and there is some polarization of the materials subject to the applied electric field. The field can travel at light speed, material polarization can be fast or slow, and actual movement of the mass of the electron is slowest.

In the conventional electric circuit there is no electron production or destruction, they are only moved around. It is possible to take electrons away from or add a surplus of electrons to a metal that is insulated. This affects the charge balance of the metal. Still the electrons are moved, not created or destroyed.

Electron production happens at the energy level you would find around a neutron star or black hole. A super high energy photon decays to an electron / positron pair, pair production. Free neutrons have a half life of ~ 20 minutes and decay to an electron and proton. Don't ask me how I know, I don't.

The university I went to, if I had Al Gore's money I would sue for .. well something, doesn't matter what (I am so well trained). They need to be sued a few (more) times. The 45 seconds the professor spent on the proof where the voltage gradient disappears inside the conductor, yielding skin effect, ... That's why we need ITunes U, so we can hit replay several times or shop around a bit.

http://en.wikipedia.org/wiki/File:Feynman_diagram_for_Pair_Production.svg

 

[mivey]

If energy travels around the concuctor rather than through it, why does resistance in the conductor reduce the amount of energy delivered?

One reason is that the conductor is not perfect and is parasitic in that it acts as a distributed load and absorbs some of the energy.

Why does this energy follow the path of the conductor?

Because the magnetic field and electric field also follow the conductor. The magnetic field is centered around the current-carrying conductor. The radial electric field is between the conductors on either side of the load. Both fields are perpendicular to the direction of energy flow towards the end load.

Why do we even need a conductor?

We don't. But if we did not have it, we would be shooting energy out into the air like a radio signal. The conductor allows us to essentially create a waveguide to direct the energy more precisely to our load.

There has to be something moving through the conductor.

Sure. Charges are moving through the conductor. Heat is also being created in the conductor. As the AC signal changes, there are internal fields moving as the internal current creates counter forces because the wire has inductance.

I always figured the field around a conductor carrying current was more of a by product.

The field is a mechanism to accomplish what we want: delivering energy to the load at the end.

At transformers we have a gap to jump. But if you had one turn on each side of the transformer not much energy would be passed on and in fact we would essentially short circuit the primary in most cases. We intensify the field by using multiple turns, this creates more inductance and reduces the amount of current in the primary so it doesn't have short circuit conditions anymore.

OK. So we want a stronger field to get a better link to the secondary side. We did not choose a bigger wire did we? The energy is exchanged through the fields.

Just some things that don't quite make sense to me if (nearly all) the energy travels outside the conductor.

Keep asking questions and reading. It will clear up.

 

[mivey]

Further to what kwired stated:

The two authors did not derive a quantitative relationship for the energy traveling outside the conductors of the circuit, but only when applied to the resistance connected to the ideal conductors of the circuit.

What they did not derive was either referenced in links or considered common knowledge. Perhaps you should read some of the references.

This makes the content of their paper more of an opinion than science based on numbers.

Hardly. Perhaps you have derived some quantitative relationships to support your opinions? If so, please share with the rest of us.

 

[mivey]

The energy does travel in the EM wave. It is not carried in the electrons. I was taught this in school by professors who know a lot more about this than I do.

How else do you explain radio waves?

Exactly. One must be able to move beyond circuit theory and understand the link to physics and field theory.

You can't have current flow without an EM field, so its kind of arbitray to say which is a product of the other.

Not real arbitrary. We can model which comes first although in the transient state there is a lot of back and forth. There are some good papers out there on the transient activity in circuits.

A similar thing happens with voltage and current. Its tempting to say the current flow is produced by the voltage, but if you look at a resistor, the current flow through the resistor causes a voltage drop.

Thus becomes the difference in an EMF and a voltage.

Its kind of like asking which comes first, the chicken or the egg. You can't have one without the other except in special cases.

But we can have cause and effect to model which comes first.

 

[mivey]

Fascinating but I can't buy into that. The size and shape of both the electric and magnetic fields are determined by the insulating media as observed through experimentation. That means that propagation rate down the wire would be determined by the insulation - which it isn't. Propagation rate of energy from end to end of a wire has been shown to be dependant on the material of the conductor; not the outside wrapping.

Based on what source of information? Is this some mechanical engineering theory? The electronics and electrical engineering world know that the propagation rate is mostly based on the conductor spacing and the permittivity of what is in between.

From your sources:

Feynman was not disputing that the propagation rate is mostly based on the conductor spacing and the permittivity of what is in between. That is pretty much common knowledge.

In your own article, Feynman called the theory you get when you extend the Poynting Vector outside it's limits as "nuts". Considering how much work he did with the Poynting Vector that's a pretty big condemnation.

He was not condeming the theory at all. The point he was making was that our normal intution made the theory seem nuts.

What he said was that there are other solutions to the formula for the field energy density and flux. However, the ones derived agree with experiments and have not been proven wrong and are the ones everyone agrees with:

There are, in fact, an infinite number of different possibilities for u and S, and so far no one has thought of an experimental way to tell which one is right! People have guessed that the simplest one is probably the correct one, but we must say that we do not know for certain what is the actual location in space of the electromagnetic field energy. So we too will take the easy way out and say that the field energy is given by Eq. (27 .14). Then the flow vector S must be given by Eq. (27 .15).
...
Anyway, everyone always accepts the simple expressions we have found for the location of electromagnetic energy and its flow. And although sometimes the results obtained from using them seem strange, noboby has ever found anything wrong with them-that is, no disagreement with experiment. So we will follow the rest of the world-besides, we believe that it is probably perfectly right.
...
We found two such expressions as possible expressions for the energy when we were doing static problems...Now we know which is the right one. Similarly, we have found the formula for the magnetic energy that is correct in general. The right formula for the energy density of dynamic fields is Eq (27.14)

Feynman thought it was nuts and refused to pursue it. That while finding the equations to be accurate within their limited scope.

That is not true. What he actually said was that it seemed nuts when compared to intuition, but that the intuition was wrong. He also noted that it should not cause us too much stress that the truth contradicts intuition because, for this topic, it was rarely important.

You no doubt begin to get the impression that the Poynting theory at least partially violates your intuition as to where energy is located in an electromagnetic field. You might believe that you must revamp all your intuitions, and, therefore have a lot of things to study here. But it seems really not necessary. You don't need to feel that you will be in great trouble if you forget once in a while that the energy in a wire is flowing into the wire from the outside, rather than along the wire. It seems to be only rarely of value, when using the idea of energy conservation, to notice in detail what path the energy is taking.

 

[mivey]

Mivey,
As always, right on target.

Astounding thread of thought.

I enjoy going back through and brushing up on this stuff. I always seem to learn something new or get a better understanding. I just wish I could remember everything. Reminds me of the joke: "I finally got it all together...but forgot where I put it".