Do electrons "move"?
- Thread starter Cretin
- Start date
Electron is a dynamic particle. This means it cannot rest
in Maxwell's equations and somehow electron must move
( without moving rectilinearly).
At the end of the XIX and the beginning of the XX centuries many scientists
(Abraham, Fitzgerald, Poincare, Lorents, Einstein ) were interested
in the question: What will take place, if Maxwell's rest electron begins
to move - rectilinearly? All of them came to the conclusion that there
would be radical changes with the electron. Later these changes were
described by the Lorentz transformations and SRT.
======================== ..
in Maxwell's equations and somehow electron must move
( without moving rectilinearly).
At the end of the XIX and the beginning of the XX centuries many scientists
(Abraham, Fitzgerald, Poincare, Lorents, Einstein ) were interested
in the question: What will take place, if Maxwell's rest electron begins
to move - rectilinearly? All of them came to the conclusion that there
would be radical changes with the electron. Later these changes were
described by the Lorentz transformations and SRT.
======================== ..
The problem of popularization the knowledge about electron.
1900, 1905, 1913
Planck, Einstein and Bohr found the energy of electron as: E=h*f.
1916
Sommerfeld found the formula of electron : e^2=ah*c,
1928
Dirac found two more formulas of electrons energy:
+ E=Mc^2 and - E=Mc^2.
According to QED in interaction with vacuum electrons
energy is infinite: E= ∞
The energy of electron in the simplest atom is:
E= - me^4/ 2h*^2 = -13,6 eV
The negative mark of energy shows that electron is tied in atom.
Electron is a particle - corpuscular and it is a wave too.
===
There is an old Indian parable of the blind men and the elephant.
Every of them touched different parts of elephant and said:
it is like a snake, like a ball, like a tomb . . . etc
Doesnt their knowledge about elephant is similar to our knowledge about electron ?
=.
In the highest level we still dont know what kind of particle (animal) we are dealing.
============ .
1900, 1905, 1913
Planck, Einstein and Bohr found the energy of electron as: E=h*f.
1916
Sommerfeld found the formula of electron : e^2=ah*c,
1928
Dirac found two more formulas of electrons energy:
+ E=Mc^2 and - E=Mc^2.
According to QED in interaction with vacuum electrons
energy is infinite: E= ∞
The energy of electron in the simplest atom is:
E= - me^4/ 2h*^2 = -13,6 eV
The negative mark of energy shows that electron is tied in atom.
Electron is a particle - corpuscular and it is a wave too.
===
There is an old Indian parable of the blind men and the elephant.
Every of them touched different parts of elephant and said:
it is like a snake, like a ball, like a tomb . . . etc
Doesnt their knowledge about elephant is similar to our knowledge about electron ?
=.
In the highest level we still dont know what kind of particle (animal) we are dealing.
============ .
This was an interesting thread until someone actually decided to question the notion of motion. No less a light than Galileo Galilei had to recant before the Inquisition of the Church that his observations implied that the earth moved around the sun. Nevertheless, his parting statement Eppur si muove (Yet, it moves)has held up longer than those of contrary beliefs. And what did Galileo and his contemporaries know about electrons? Nothing.
The mind is a wondrous thing: weightless, unbounded by time or distance, capable of exploring new galaxies and far-away places and the infinitesimal wonder of sub-atomic distances. It appears the mind operates on a matrix of physical reality (stuff you can sense and measure) but this has never been proven. Indeed, the tenuous connection between mind and brain is pretty much still unexplored except by philosophers. Yet cogito, ergo sum. From which you can draw no further conclusions.
I like living in physical reality, even if my observations and the conclusions I make from those observations are philosophically suspect. So be it. In my world electrons have mass and momentum but are point objects that occupy no space. How many electrons (or angels) can fit on the head of pin? Photons have energy and momentum and (in one sense, via the electromagnetic field) occupy all of space. And I observe that electrons in accelerated motion create photons, and decelerated photons can decay into electron/positron pairs. What a wonderful Cosmos I happen to occupy!
To the OP, who may have a promising career in electrical engineering or physics if the philosophical implications of motion are ignored, the answer is: Yes, electrons move. Just dont try to argue this in your philosophy courses. Leave those puppies behind in the lab until you return to the real world.
I work with a particle accelerator that creates a 1.7 megavolt electrostatic acceleration field. We feed negative ions into it and they come roaring out the other end as positive ions with upwards of six million electron-volts of energy. A 6 MeV ion will penetrate several micrometers into the hardest materials. The engineers who designed this machine were careful to avoid accelerating electrons along with the negative ions. 1.7 MeV electrons produce copious x-ray emissions when the hit almost anything (yes, electrons move) so there are strategically placed permanent magnets to deflect the electrons out of the way before they acquire much energy from the accelerating field. All this takes place in a pretty good vacuum of course.
If the same 1.7 megavolts were to be applied across a wire, a current would flow in the wire but the electrons would not move very fast. Things are pretty close together in a wire so it is a bit like trying to make your way through a crowd to the restroom at half time of a football game. The urgency is there, but you cant just bowl your way through to your destination. And the whole crowd is heading for the restroom with similar urgency. The urgency is like the electrical field the electron sees, strong but not irresistable. So just go with the flow, seeking gaps of opportunity to slip a little further along. Whoops! Not so fast, someone just stepped into the spot you were aiming for. Eventually you reach your destination and notice that just about as many people are entering the restroom as are leaving it, forming a more or less steady current of warm bodies. This is Kirchoffs Law as applied to stadium restrooms. I could offer other analogies to electrical circuits, but you can only push an analogy so far before it falls apart.
Finally, consider the electroplating process. Here real material is moved (as ions in solution) from one electrode to another. The speed at which this is done is more or less linearly proportional to the current in the connecting wires, not the speed of the electrons in the wires. The only thing that moves really fast in all these electrical situations are the electromagnetic fields, in which the electrons are just along for the ride.
The mind is a wondrous thing: weightless, unbounded by time or distance, capable of exploring new galaxies and far-away places and the infinitesimal wonder of sub-atomic distances. It appears the mind operates on a matrix of physical reality (stuff you can sense and measure) but this has never been proven. Indeed, the tenuous connection between mind and brain is pretty much still unexplored except by philosophers. Yet cogito, ergo sum. From which you can draw no further conclusions.
I like living in physical reality, even if my observations and the conclusions I make from those observations are philosophically suspect. So be it. In my world electrons have mass and momentum but are point objects that occupy no space. How many electrons (or angels) can fit on the head of pin? Photons have energy and momentum and (in one sense, via the electromagnetic field) occupy all of space. And I observe that electrons in accelerated motion create photons, and decelerated photons can decay into electron/positron pairs. What a wonderful Cosmos I happen to occupy!
To the OP, who may have a promising career in electrical engineering or physics if the philosophical implications of motion are ignored, the answer is: Yes, electrons move. Just dont try to argue this in your philosophy courses. Leave those puppies behind in the lab until you return to the real world.
I work with a particle accelerator that creates a 1.7 megavolt electrostatic acceleration field. We feed negative ions into it and they come roaring out the other end as positive ions with upwards of six million electron-volts of energy. A 6 MeV ion will penetrate several micrometers into the hardest materials. The engineers who designed this machine were careful to avoid accelerating electrons along with the negative ions. 1.7 MeV electrons produce copious x-ray emissions when the hit almost anything (yes, electrons move) so there are strategically placed permanent magnets to deflect the electrons out of the way before they acquire much energy from the accelerating field. All this takes place in a pretty good vacuum of course.
If the same 1.7 megavolts were to be applied across a wire, a current would flow in the wire but the electrons would not move very fast. Things are pretty close together in a wire so it is a bit like trying to make your way through a crowd to the restroom at half time of a football game. The urgency is there, but you cant just bowl your way through to your destination. And the whole crowd is heading for the restroom with similar urgency. The urgency is like the electrical field the electron sees, strong but not irresistable. So just go with the flow, seeking gaps of opportunity to slip a little further along. Whoops! Not so fast, someone just stepped into the spot you were aiming for. Eventually you reach your destination and notice that just about as many people are entering the restroom as are leaving it, forming a more or less steady current of warm bodies. This is Kirchoffs Law as applied to stadium restrooms. I could offer other analogies to electrical circuits, but you can only push an analogy so far before it falls apart.
Finally, consider the electroplating process. Here real material is moved (as ions in solution) from one electrode to another. The speed at which this is done is more or less linearly proportional to the current in the connecting wires, not the speed of the electrons in the wires. The only thing that moves really fast in all these electrical situations are the electromagnetic fields, in which the electrons are just along for the ride.
It's been a long time since I was on this thread and may have missed it, but did anyone estimate drift velocity and thermal velocity?
In a purely classical sense, which may not be very accurate but will certainly give order of magnitude comparisons, It's not that hard to work out.
We all know the speed of light is:
\(C\ \approx\ 3\times10^{9}\ m/s\)
Which is approximately the speed of the electric field in copper.
Using an ideal gas model for free electrons in a copper lattice we can estimate the RMS thermal velocity as:
\(V_{RMS}\ =\ \sqrt{\frac{3k_{B}T}{m_{e}}} \approx\ 10^{6}\ m/s\ \ \ \ at\ room\ temperature.\)
In reality, because a copper lattice in NOT an ideal gas, the value is more in the range \(V_{RMS}\ =\ 10^{5}\ m/s\)
Finally, given that current is Coulombs/sec we can estimate the drift velocity of electrons at 1 Amp through a #14 copper wire as:
\( V_{D}\ \approx\ \frac{I}{eNA}\ m/s\)
Where:
\( I\ =\ 1\ is \ the\ current\ in\ Amps\)
\( e\ =\ 1.6\times10^{-19}\ Coulombs\ \ \ is\ the\ charge\ on\ an\ electron\)
\( N\ \approx\ 8.5\times 10^{28}\ m^{-3} \ \ \ is\ the\ number\ of\ copper\ atoms\ per\ cubic\ meter\ (only\ one\)
\(electron\ per\ atom\ is\ usually\ contributed\ to \ the\ free\ electron\ gas)\)
\( A\ \approx\ 2\times10^{-6}\ m^{2}\ is\ the\ cross\ sectional\ area\ of\ the\ wire\)
We get
\( V_{D}\ \approx\ 4\times\10^{-5}\ m/s\)
So, the electron drift velocity due to current flow is very slow compared to the speed of the electric field, or the chaotic motion due to temperature.
In a purely classical sense, which may not be very accurate but will certainly give order of magnitude comparisons, It's not that hard to work out.
We all know the speed of light is:
\(C\ \approx\ 3\times10^{9}\ m/s\)
Which is approximately the speed of the electric field in copper.
Using an ideal gas model for free electrons in a copper lattice we can estimate the RMS thermal velocity as:
\(V_{RMS}\ =\ \sqrt{\frac{3k_{B}T}{m_{e}}} \approx\ 10^{6}\ m/s\ \ \ \ at\ room\ temperature.\)
In reality, because a copper lattice in NOT an ideal gas, the value is more in the range \(V_{RMS}\ =\ 10^{5}\ m/s\)
Finally, given that current is Coulombs/sec we can estimate the drift velocity of electrons at 1 Amp through a #14 copper wire as:
\( V_{D}\ \approx\ \frac{I}{eNA}\ m/s\)
Where:
\( I\ =\ 1\ is \ the\ current\ in\ Amps\)
\( e\ =\ 1.6\times10^{-19}\ Coulombs\ \ \ is\ the\ charge\ on\ an\ electron\)
\( N\ \approx\ 8.5\times 10^{28}\ m^{-3} \ \ \ is\ the\ number\ of\ copper\ atoms\ per\ cubic\ meter\ (only\ one\)
\(electron\ per\ atom\ is\ usually\ contributed\ to \ the\ free\ electron\ gas)\)
\( A\ \approx\ 2\times10^{-6}\ m^{2}\ is\ the\ cross\ sectional\ area\ of\ the\ wire\)
We get
\( V_{D}\ \approx\ 4\times\10^{-5}\ m/s\)
So, the electron drift velocity due to current flow is very slow compared to the speed of the electric field, or the chaotic motion due to temperature.
russ_hensel
- Joined Jan 11, 2009
- 825
I think you mean the photon? Even if so I think the statements are wrong. In my physics courses photon motion was almost always in a straight line ( with occasional disconunities ). Can you site a source?
Electron is a dynamic particle. This means it cannot rest
in Maxwell's equations and somehow electron must move
( without moving rectilinearly).
At the end of the XIX and the beginning of the XX centuries many scientists
(Abraham, Fitzgerald, Poincare, Lorentz, Einstein) were interested
in the question: What will take place, if Maxwell's rest electron begins
to move - rectilinearly? All of them came to the conclusion that there
would be radical changes with the electron. Later these changes were
described by the Lorentz transformations and SRT.
======================== ..
Source-1.
Max Abraham's work is almost all related to Maxwell's theory and electron.
FitzGerald light contraction is effect of light's motion.
Henri Poincaré' On the dynamics of the electron'
H.A.Lorentz 'Theory of electrons '
Einstein : "On the Electrodynamics of Moving Bodies",
====================..
Source-2: my own interpretation the philosophy of physics.
==..
Maxwell's theory is not an isolate system of equations.
This theory is tied with SRT.
This mean that electron in Maxwell's theory changes its behavior
when it translates in SRT region.
You cannot take Maxwell's equations as never changed field.
==.
Not so.
They are perfectly compatible with special relativity, but could be compatible with other different laws since they are quite independent.
This, however, does not address my point which challenged your claim that Maxwell's equations require the electron to be in motion.
I ask you to demonstrate this requirement in Maxwell's equations.
The Universe as whole is one harmony system:
one law is tied with other law and so is . . . etc. . . . .
#
Maxwell's equations say nothing about electron.
But there isn't Maxwell's equations without electron
It is my own opinion that electron cannot rest in the Maxwell's equations .
At last.
No so. They are field equations.
Maxwells equations are independent of the source or form of that charge. Are you suggesting they do not apply to other charges, such as ions, positrons, protons etc?
Surely equations of any sort are a matter of mathematics, not opinions?
Maxwell's equations are not independent of its source electron.
Maxwell's equations depend on an electron.
Maxwell's equations isn't isolate system.
There isn't Maxwell's theory without SRT and vice versa.
Source .
Max Abraham's work is almost all related to Maxwell's theory and electron.
FitzGerald light contraction is effect of light's motion.
Henri Poincaré' On the dynamics of the electron'
H.A.Lorentz 'Theory of electrons '
Einstein : "On the Electrodynamics of Moving Bodies",
====================..
Excuse my poor English
I want to say that the electron is the father of Maxwell's equations.
Without electron there isn't Maxwell's em waves
( dualism of wave-particle)
==..
Perhaps you should check your dates
Maxwells equations 1860 - 1871
Thompson's discovery of the electron 1897
In fact the history of both makes good reading.
http://www.ieeeghn.org/wiki/index.php/Milestones:Maxwell's_Equations,_1860-1871
http://www.aip.org/history/electron/
Maxwell created mechanical model of em waves
Thompson created 'pudding atom'
History of physics is not the way you think.
Why?
Because even now we don't know what electron is.
=..
So both of them were very clever persons who are remembered for more than one discovery in physics.
Are you denying that Thompson discovered the electron nearly thirty years after Maxwell published his electromagnetic equations?
This is just plain rubbish.
There are many things we know of but do not fully understand. How does not fully understanding them alter their discovery?
I understand you:
An egg cannot be before a hen.
At first must be the hen and after the egg.
Question: where the quantum hen come from?
=.
Thank you for conversation.
All the best.
socratus
