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Conventional Current

by Oscar Wilde
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rosie
#19
May6-09, 02:05 PM
P: 39
sorry - I meant to add - those who disagree with the movement of electrons comprising the flow of current. I'll provide that list tomorrow. I've got to search through my books and it takes ages because - as mentioned - I'm blind as a bat.
chroot
#20
May6-09, 02:42 PM
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Quote Quote by rosie View Post
Warren - This has been a remarkably ascerbic attack. I have very restricted vision and am obliged to use all kinds of sight aids. Possibly why I do not read enough. But, for my age, I believe I am extremely well read. And there is nothing wrong with my reasoning nor my education in physics which I admit is ongoing. That's why I joined the forum.
You appear to have very little interest in education; instead, the bulk of your posts are strawmen and attacks against them. You seem eager to find flaws in a model that you clearly do not understand at all.

However to get back to the point. Could you please reconcile Pauli's exclusion principle with the 'flow of electrons' through your standard electric circuit?
Reconcile? What does the Pauli exclusion principle have to do with the movement of electrons through a conductor in the first place?

As I understand it electrons belong to the Lepton family. They are charged. They have mutually exclusive orbits around a nucleus. How then do they 'follow each other' however it's done - through electric circuitry? This could only be done if they simultaneously 'lost their charge'.
In a conductor, some electrons have energies sufficient to allow them to move freely throughout. The electrons in a conductor can be modeled reasonably well as a gas of free electrons. The electrons are not entirely free, of course, since they do interact with the atoms, but the effect is small.

If you apply an electric field, these mobile electrons will feel a force, and will begin moving. Their thermal energies are relatively high, though. They bounce around randomly inside the conductor with speeds approaching a million miles an hour, but the electric field biases them to travel a little more easily in one direction than the other. Over time, that bias causes them to slowly move through conductor. The speed at which they move through the conductor, the bias, is called the "drift velocity." This speed is on the order of centimeters per hour in normal situations. That's right, an individual electron's progress through a wire is slower than that of a snail.

Regarding your explanation of 'fire'. A 'chemical reaction' that somehow requires oxygen to enable it does nothing to explain the thing itself. All the molecules and all the atoms that go into that 'event' come out in tact.
When you burn something, you modify its molecules. You combine carbon atoms with oxygen atoms, say, and produce carbon dioxide. The atoms are the same, but they have been rearranged. That rearrangement liberates energy.

In the same way, a book on the edge of a table is one valid arrangement of books and tables. If the book falls off, energy will be released. The book might then end up under the table. That's also a valid arrangement, but it has less energy than the previous arrangement. Neither the book nor the table has changed in the process, but their arrangement is different, and energy has been released.

if this forum is simply based on a system of 'you ask the question and I'll give the answer' then I have lost the plot. I was rather hoping that we could explore complex questions. They keep me awake. It would help if I could find others who also ask these questions?
You are more than welcome to ask questions. You are absolutely not welcome to propose your own theories and tout them as being better than those of accepted, mainstream science. That's particularly troublesome when you make it clear that you don't even understand what accepted, mainstream science says in the first place.

That 'fire' in the sun is the result of a nuclear reaction is exactly the same as saying that the fire on the circuit was a chemical reaction. It says nothing about the nature of 'fire'. Is it photons? Is it pure energy? What?
"Fire" is a common name for any chemical reaction involving oxygen. It has no deeper physical meaning.

- Warren
JoAuSc
#21
May6-09, 03:49 PM
P: 200
Quote Quote by rosie View Post
I think that the flaw in this explanation is that one electron nudges another. Electrons will not 'nudge' up against each other any more than like poles on a bar magnet can 'nudge' together. Then too, the time taken for these 'series' of interactions exceeds the time of actual flow of current which is known to be instantaneous.
Quote Quote by chroot View Post
This is a strawman argument. No physical theory contends that electrons move through conductors by being nudged in turn, so your argument is moot.
Maybe I should've used a better word than "nudge". I did not mean to imply that electrons bounce into each other like billiard balls, or line up behind each other one-by-one, but rather that:
  1. when you apply an electric field to a small portion of a wire loop, the electrons will move in the opposite direction (since they're negatively charged), and this will cause the charge density to change from 0 everywhere to positive in one direction of the portion of wire and negative in the other direction;
  2. the electrostatic force ensures that any charge density created will push forward more electrons, which will in turn create a new charge density change; and
  3. this means that a charge density wave will propagate around the wire.

This example shows how electrical power can be transmitted down a wire. You can imagine a similar example with water in a loop of pipes, where you would only have to move the water a little bit to get all of the rest of the water to move a little bit.

I don't claim that this is exactly what happens; for example, I didn't mention drag, I didn't mention the random thermal motions the electrons were doing before any electric field was applied, and in the long term (over the time it would take to get the electric field to full strength) the electron motion would be less wavey and more uniform throughout the wire, but I hope I've made myself clearer.

Quote Quote by rosie View Post
I know for a fact that electric current flow has nothing to do with the flow of electrons. They stay right where they are - inside the atoms.
In a metal, not all electrons are stuck to atoms. The higher-energy electrons (the "conduction electrons") can travel almost freely within the metal.

It's difficult to explain why the Pauli exclusion principle does not prevent electrons from traveling through a metal. One explanation is this: When an electron is in an atom, it is in a quantum state (or a superposition of them), and when an electron is a conduction electron, it is also in a quantum state, in this case one which is spread out among the entire metal...I think. (I posted a question about this a little while ago, but got no replies.) Anyway, conduction electrons move in conduction electron states, and thus don't have to worry about using the atomic states which would be forbidden under the Pauli exclusion principle.

Quote Quote by rosie View Post
That 'fire' in the sun is the result of a nuclear reaction is exactly the same as saying that the fire on the circuit was a chemical reaction. It says nothing about the nature of 'fire'. Is it photons? Is it pure energy? What?
"Fire" is a process. It is a chemical reaction. Maybe you're thinking about "what is a flame?", in which case I can tell you it's very hot gases which glow. They are hot because the chemical reaction releases a lot of energy. I don't know if they glow from being so hot (i.e., I don't know if thermal radiation is strong enough at visual frequencies at the temperature of a fire to explain its glow), or if they glow due to chemical reactions which are occurring within the gas or the particles in the flame.
rosie
#22
May6-09, 03:51 PM
P: 39
Ok. Here's the situation. I have a simple flyback switching circuit with a load in series with an inductor. A diode is placed in parallel to both resistor and inductor and returns to the battery. The switch is opeated with a 555 powering a MOSFET. The MOSFET has a protection body diode so that current is enabled during the off and on period of each switching cycle. I can arrange the frequency of the switch to operate at, say, 100KHz. The apparatus is powered by a battery. I generate a voltage across the load resistor and through my scope meter can see that the waveform is above zero for say, 90% of each cycle which corresponds to the on period of the duty cycle. Then the switch opens - the fields in the inductor collapse and the waveform moves in a sharp voltage spike before returning to zero. That spike goes way below zero. and this energy, from collapsing fields in the inductor can be seen to cause a small but measurable increase in the voltage across my battery showing that it is partially recharging the battery. Bear in mind that the circuit integrity is retained during the off period of the duty cycle by virtue of the MOSFET's protection body diode. This is well known. Nothing new. Not hypothetical.

It has to be due to the 'negative' voltage causing this fractional recharge in the battery - which implies that there is a definite negative curent flow. The v squared over r analysis of the wattage at the resistor corresponds to both cycles including that sharp spike. In other words the resistor gets hot.

Now. Electrons first 'flowed' to establish the positive current flow which resulted in the voltage across the resistor above zero. Then they 'flowed' to establish the negative current flow back through the resistor and then to the battery. As mentioned, the battery is seen to partially recharge. But the electron cannot be responsible for both a negative and a positive current flow. So it must be something other than the electron that managed the second half of that flow.

Then. If the flow of 'loose electrons' in metal stuctures determine a postive current flow do 'loose protons' then allow for a negative current flow? To the best of my knowledge there are no loose protons or electrons in either. Just speculatively there may be. But that's not scientific.

That's another reason that I question conventional models.
rosie
#23
May6-09, 04:12 PM
P: 39
JoAuSc - I have just seen your post. The above was meant for Warren regarding the properties of current flow. It's so nice to get a thoughtful reply. Thanks for that. I'll study it tomorrow. Right now I'm tired and feeling a bit bruised.

Rosie
rosie
#24
May6-09, 04:23 PM
P: 39
Warren - by the way, I've actually done that experiment. I think it's called a flyback circuit used for powering battery operated drills and such like. The point is that if you put the diode to a second battery connected to the supply battery only through the negative rail - you can actually see the recharge cycle in process. I think it's used - partially - in that drill system - but am not sure. The point is that when you use it precisely for generating heat - then there's a marginal increase in efficiency.
chroot
#25
May6-09, 04:31 PM
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If electrons travel one direction, you're free to call that "positive current." If the electrons travel in the opposite direction, you're free to call that "negative current." Both are still due to the movement of electrons.

- Warren
rosie
#26
May6-09, 04:35 PM
P: 39
Ok. Then what flows when you use a positively ionised battery?
chroot
#27
May6-09, 04:41 PM
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What's a "positively ionized battery?"

- Warren
rosie
#28
May6-09, 04:45 PM
P: 39
What I mean is not an acid but an alkaline battery. The one's that you use in your remotes etc.
dx
#29
May6-09, 04:56 PM
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Whatever battery you use, the electrons are the ones that flow in wires.
chroot
#30
May6-09, 05:31 PM
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Quote Quote by rosie View Post
What I mean is not an acid but an alkaline battery. The one's that you use in your remotes etc.
Battery chemistry is irrelevant to the discussion of electric conduction.

By the way, you should attribute credit to whomever actually wrote your post #22.

- Warren
chroot
#31
May6-09, 06:24 PM
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Quote Quote by JoAuSc View Post
  1. when you apply an electric field to a small portion of a wire loop, the electrons will move in the opposite direction (since they're negatively charged), and this will cause the charge density to change from 0 everywhere to positive in one direction of the portion of wire and negative in the other direction;
  2. the electrostatic force ensures that any charge density created will push forward more electrons, which will in turn create a new charge density change; and
  3. this means that a charge density wave will propagate around the wire.
This is really not a good way to describe the flow of current.

An electric field can be established between the ends of a wire in virtually no time at all -- changes in the field propagate at the speed of light in the material (c for conductors hanging in vacuum, about one foot per nanosecond for a conductors embedded in fiberglass).

As soon as the electric field has been established, electrons will respond to it. It is not necessary for charges to move, or for a wave of charge density to propagate through the wire. In fact, that charge density wave does not exist; even a small imbalance of charge density from one part of the wire to the next would result in extremely large forces. The charge density is uniform throughout the conductor (ignoring edge effects), and is not affected by the application of a uniform electric field.

- Warren
Phrak
#32
May6-09, 07:42 PM
P: 4,512
For a step change in voltage applied to one end of a straight conductor, an electric field, magnetic field, and the current change, all in phase, down the length of the wire. Would the net charge porpagate as something of a shock wave, everywhere zero except at the step propagating near c, or will the charge be simply picked up along the way. I can't seem to see get the equation.
DruidArmy
#33
May6-09, 07:55 PM
P: 8
Hi,
There may be a positive flow (conventional current) moving opposite to the electron flow, as evidenced by the positive Canal Rays which exit the cathode.

Don't you agree?
rosie
#34
May7-09, 12:19 AM
P: 39
Warren
"By the way, you should attribute credit to whomever actually wrote your post #22".

I'm actually flattered that you assume it was written by someone else. It was an experiment that I did to see if transients could be used to enhance efficiency. As you know these are 'thrown away' as a rule - because they're redundant to the objects of most applications. If you send me your email address I'll download the details of the experiment. It was all duly recorded. Not ground breaking - but interesting. Post 22 was indeed written by me. Who else? I'm the only member of my family who is interested in physics. Truth is I think I used that example to try and show you that I do know a little bit about physics. But - before you state the obvious. I really do know a very little bit. I know this because there's so much out there that I don't know.

Classical theory is really not as complete as you imply. I agree that quantum electrodynamics is amazing. But - as you said - it is all modelled on concepts - of necessity. Heisenberg's uncertainty principle is the foundation of all quantum physics and it was actually a cop out. Gravity - which you've described in a sentence - has never been fully reconciled with Einstein's theories on relativity. They're giants - Pauli, Heisenberg, Maxwell - all. But to the best of my knowledge none of them ever pretended to understand everything. The search is still on for the unifying principle. And that has to include gravity - dark energy and matter - and certain questions on locality that - thus far are known as paradoxes. Lots of questions Warren.

If I presume to question classical interpretations of current flow its because I can't buy into or get my head around one simple question. In the process of manufacture and refinement - electrons - extraneous to the material - free floating and from nowhere - attach themselves to the material of that amalgam. Just that. Where do these free floating electrons come from? And how do they attach?

I took the trouble to look up the definition of current flow. Your explanation is consistent with this - but also includes the requirement for 'free floating protons' in a battery supply source. Do these also move through the wire that they connects them to those free floating electrons. Sorry. I just don't buy it.

For me personally there are many more questions here than answers. I promised you a list of those physicists who do not 'buy into' the electron flow model. Starting with Pauli - his princple forbids the possibility of leptons 'sharing a path' - anywhere in or out of an atom. Paul Dyson - conceptual physics and Gary Zukov - dancing wu li masters. This latter is authoritative as it was approved and edited by a huge number of his colleagues. I'll add to that list but that's a start.
rosie
#35
May7-09, 01:30 AM
P: 39
Sorry Warren. I don't suppose I should post two in one day - but there's another point. Let's say that we simply apply a battery in series with a load. The electrons all shift in one direction. Do they eventually spill out into the battery?
chroot
#36
May7-09, 02:58 AM
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Quote Quote by rosie View Post
Classical theory is really not as complete as you imply.
You are correct, physics is not complete. That does not mean that our models of very basic phenomena like conduction are also incomplete.

Heisenberg's uncertainty principle is the foundation of all quantum physics and it was actually a cop out.
The HUP is absolutely not the foundation of quantum mechanics. Quantum mechanics is based on a number of postulates, none of which make any reference to the HUP. The HUP is actually a derivation from those postulates -- hardly "fundamental" at all.

Gravity - which you've described in a sentence - has never been fully reconciled with Einstein's theories on relativity. They're giants - Pauli, Heisenberg, Maxwell - all. But to the best of my knowledge none of them ever pretended to understand everything. The search is still on for the unifying principle. And that has to include gravity - dark energy and matter - and certain questions on locality that - thus far are known as paradoxes. Lots of questions Warren.
Yes, yes, lots of questions, indeed. Unfortunately, electron conduction in wires is not one of them.

In the process of manufacture and refinement - electrons - extraneous to the material - free floating and from nowhere - attach themselves to the material of that amalgam. Just that. Where do these free floating electrons come from? And how do they attach?
What in the world are you talking about? The manufacture of what? Wires? Wires are made of metal, and, like all macroscopic substances, are always extremely close to being electrically neutral.

I took the trouble to look up the definition of current flow. Your explanation is consistent with this - but also includes the requirement for 'free floating protons' in a battery supply source. Do these also move through the wire that they connects them to those free floating electrons. Sorry. I just don't buy it.
Currents of electrons don't require complementary currents of protons at all! Hydroelectric generators do it quite well, with no movement of protons at all. Chemical batteries employ the conduction of protons, but that's no surprise -- that's how batteries were designed to work.

A chemical battery involves so-called "redox" reactions, which involve the movement of electrons from molecule to another. In other words, electrons are stripped from some molecules and deposited on others. The battery is cleverly designed so that, while the positive ions are able to flow easily through the battery's liquid, the electrons cannot, and are forced to move through a circuit instead.

For me personally there are many more questions here than answers.
It seems that you have never considered reading a book, since the answers to your questions are readily available.

I promised you a list of those physicists who do not 'buy into' the electron flow model. Starting with Pauli - his princple forbids the possibility of leptons 'sharing a path' - anywhere in or out of an atom.
The Pauli Exclusion Principle says that no two particles can have the same quantum numbers. Quantum numbers represent the available states of some system with some quantized quantity. It does not apply to the movement of electrons in conductors, because conductors have a continuum -- an infinitude -- of available states. Your argument is without merit.

Paul Dyson - conceptual physics and Gary Zukov - dancing wu li masters.
I think you'd need to provide specific quote for these fellows to actually give any weight to your argument. Besides, if your arguments had any weight of their own, you probably would not feel compelled to grasp at straws as slippery as these.

The discussion of personal theories is disallowed here. If you wish to gain a better understanding of existing physical theory (your understanding is appalling), feel free to continue the discussion. If you wish to tout your own personal theory, though, I'm afraid you'll have to find greener pastures.

- Warren


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