electron flow
- Thread starter frank
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Re: electron flow
I tried a Google search for this and came up with a lot of links dealing with the speed of electrons, seems to be a hot topic for computer designers.
From what I could understand and I may be wrong, voltage does not effect speed other things may like the type of material you are flowing through.
Here are a couple of links but there are plenty more if you do a little searching.
Current Flow
Here is a quote from the this link.
SciForums
[ April 27, 2003, 05:38 AM: Message edited by: iwire ]
I tried a Google search for this and came up with a lot of links dealing with the speed of electrons, seems to be a hot topic for computer designers.
From what I could understand and I may be wrong, voltage does not effect speed other things may like the type of material you are flowing through.
Here are a couple of links but there are plenty more if you do a little searching.
Current Flow
Here is a quote from the this link.
This next link is a Science Forum topic about this subject. (over my head)
SciForums
[ April 27, 2003, 05:38 AM: Message edited by: iwire ]
bphgravity
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Re: electron flow
I like to use the water anology. Think of a pipe full of water. When pressure is applied to one end, instantneously, water comes out the other end. Now the individual water molucules have not moved all that far, but the effect of the pressure is immediate. The same goes for electrical current. The energy pulse is instant and near the speed of light. The actual movement of the electrons is minimal. The term current is really scientifically incorrect terminalogy. Think of water again. Water flowing through a river is not current. Current is the collective of water flowing. So you cant think of one point in a conductor as having current. It is the entire circuit loop where flow exists.
I like to use the water anology. Think of a pipe full of water. When pressure is applied to one end, instantneously, water comes out the other end. Now the individual water molucules have not moved all that far, but the effect of the pressure is immediate. The same goes for electrical current. The energy pulse is instant and near the speed of light. The actual movement of the electrons is minimal. The term current is really scientifically incorrect terminalogy. Think of water again. Water flowing through a river is not current. Current is the collective of water flowing. So you cant think of one point in a conductor as having current. It is the entire circuit loop where flow exists.
al hildenbrand
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Re: electron flow
I've had trouble for years with thinking of current in terms of the physical reality that we live in, the Newtonian universe, (for Isaac Newton).
Ball bearings down a conduit (physically lined up one after the other and touching each other) and hydraulic examples of water in a conduit are great teaching models. But they don't go far enough to really answer the question:
Here's the stretch. . .what allows the new ball bearing to be pushed into the conduit, or the quantity of water to pumped into the pipe, is the fact that the push on this end[ caused a bearing to go out of the pipe on that end, creating a hole that the next bearing moved into, and the next beside it, and again, etc. all the way back to this end. The hole moves at "light speed" back from that end to this end even though the things, the bearing or the quantity of water, obviously only move short distances.
There are two different properties here:</font>
I've had trouble for years with thinking of current in terms of the physical reality that we live in, the Newtonian universe, (for Isaac Newton).
Ball bearings down a conduit (physically lined up one after the other and touching each other) and hydraulic examples of water in a conduit are great teaching models. But they don't go far enough to really answer the question:
The real important nub, for me, in these two models is that the push at one end appears almost instantaneously (the speed of light) at the far end of the conduit.
Here's the stretch. . .what allows the new ball bearing to be pushed into the conduit, or the quantity of water to pumped into the pipe, is the fact that the push on this end[ caused a bearing to go out of the pipe on that end, creating a hole that the next bearing moved into, and the next beside it, and again, etc. all the way back to this end. The hole moves at "light speed" back from that end to this end even though the things, the bearing or the quantity of water, obviously only move short distances.
There are two different properties here:</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Voltage</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Current</font>
al hildenbrand
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Re: electron flow
Going a little further, the analogy breaks down. Pushing water harder moves more cubic feet per minute, pushing the bearings harder means they have to move faster. This Newtonian model works in my mind's eye, because I can see this in the "real world" of my senses.
The nuclear and sub-nuclear world, however, is a place where things act like waves and particles, simultaneously, and are seperated one from the other by enormous distance yet are interconnected ("spooky action at a distance").
The electrons that we electricians think of as current are not moving in just a straight line (like the water or bearings), rather in any direction.
The idea of the voltage (the electric field) propagating at light speed, as well as the current (as the movement of the absence of electrons, or holes) becomes a much more useful model.
The bottom line:
The holes and the push are still moving at near light speed. No change in their speed as the push (voltage) goes up.
Going a little further, the analogy breaks down. Pushing water harder moves more cubic feet per minute, pushing the bearings harder means they have to move faster. This Newtonian model works in my mind's eye, because I can see this in the "real world" of my senses.
The nuclear and sub-nuclear world, however, is a place where things act like waves and particles, simultaneously, and are seperated one from the other by enormous distance yet are interconnected ("spooky action at a distance").
The electrons that we electricians think of as current are not moving in just a straight line (like the water or bearings), rather in any direction.
The idea of the voltage (the electric field) propagating at light speed, as well as the current (as the movement of the absence of electrons, or holes) becomes a much more useful model.
The bottom line:
The greater the push, the greater the flow of holes (current) through the conductor. However, the electron at any one volume, as it bounces back and forth, up and down, side to side, as the holes goes by, does so more often.
The holes and the push are still moving at near light speed. No change in their speed as the push (voltage) goes up.
al hildenbrand
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Re: electron flow
Bennie,
[ April 27, 2003, 01:39 PM: Message edited by: al hildenbrand ]
Bennie,
When you push a bearing on one end, do you see any hesitation before the bearing at the other end moves? Remember, the bearings are end to end, one against the other lined up in a single row inside a conduit just a little larger than they are.
[ April 27, 2003, 01:39 PM: Message edited by: al hildenbrand ]
bphgravity
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Re: electron flow
I don't belive there are any "holes". In a complete circuit, the flow of electrons is continuous and without gaps. The charge may have gaps, not the electrons. The electrons flow through the conductor and facilitate the electrical charge that is at the speed of light. I imagine a wheel. If grab one point along the wheel and spin it, the entire wheel spins instantaneously, meaning the energy is instant, but the actual movement of the wheel is minimal. If you place you hand ove the wheel to stop it, your hand becomes warm from friction. If you keeping spinning the wheel with one hand while trying to stop it with the other, you have created the tyipcal electrical circuit. The pushing hand is the energy generator that is creating the motion. The other hand is the resistance that accepts a portion of the distributed energy. This is like a generator that pushes the electrons in the conductor, the energy is created and resisted by loads. The flow of electrons are constant and are never less than what started. The energy they deliver is the only thing that changes.
I don't belive there are any "holes". In a complete circuit, the flow of electrons is continuous and without gaps. The charge may have gaps, not the electrons. The electrons flow through the conductor and facilitate the electrical charge that is at the speed of light. I imagine a wheel. If grab one point along the wheel and spin it, the entire wheel spins instantaneously, meaning the energy is instant, but the actual movement of the wheel is minimal. If you place you hand ove the wheel to stop it, your hand becomes warm from friction. If you keeping spinning the wheel with one hand while trying to stop it with the other, you have created the tyipcal electrical circuit. The pushing hand is the energy generator that is creating the motion. The other hand is the resistance that accepts a portion of the distributed energy. This is like a generator that pushes the electrons in the conductor, the energy is created and resisted by loads. The flow of electrons are constant and are never less than what started. The energy they deliver is the only thing that changes.
al hildenbrand
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Re: electron flow
The hole is the interesting idea in this.
Take a one inch conduit and push 7/8" bearings into it until the first one comes out the other end (let's suspend gravity. . .electrons in a wire won't run out the end if the wire is tipped down ). Pushing against the bearing on this end causes the bearing on that end to move out, and all the bearings advance.
Now two objects (bearings) can't occupy the same space at the same time, so, one bearing has to move ahead to create a space for the next bearing in line to move into. This happens in infinitely small increments, but it has to happen with holes, because the bearings can't be in the same place with each other. The hole created at that end almost instantaneously moves down the line of bearings to this end to make room for each successive bearing, and lastly the bearing that I am pushing.
Going a little further, all these ideas of bearings, water & wheels need to include movement of mass with no inertia. There is, of course a form of electrical current inertia in the form of the induced current that is created by the currents own magnetic field collapsing when the voltage is stopped (or reduced), but that is a far cry from the inertia of a moving mass.
The hole is the interesting idea in this.
Take a one inch conduit and push 7/8" bearings into it until the first one comes out the other end (let's suspend gravity. . .electrons in a wire won't run out the end if the wire is tipped down
). Pushing against the bearing on this end causes the bearing on that end to move out, and all the bearings advance. Now two objects (bearings) can't occupy the same space at the same time, so, one bearing has to move ahead to create a space for the next bearing in line to move into. This happens in infinitely small increments, but it has to happen with holes, because the bearings can't be in the same place with each other. The hole created at that end almost instantaneously moves down the line of bearings to this end to make room for each successive bearing, and lastly the bearing that I am pushing.
Going a little further, all these ideas of bearings, water & wheels need to include movement of mass with no inertia. There is, of course a form of electrical current inertia in the form of the induced current that is created by the currents own magnetic field collapsing when the voltage is stopped (or reduced), but that is a far cry from the inertia of a moving mass.
Ed MacLaren
Senior Member
Re: electron flow
These sketches that I have used in seminars might help supplement the good information above.
A "hole" is just a positively charged ion (atom that has lost an electron) which will accept a nearby free electron.
The free electrons that constitute current flow use the "holes" as "stepping stones" to move through the conductor material.
As a consequence of the movement of electrons from negative to positive, the holes can be seen to be moving from positive to negative.
Thus, the term "hole flow", sometimes used by the electronics industry to justify the conventional (positive to negative) theory of current flow, also still used in the automotive electrical field.
Ed
[ April 27, 2003, 10:29 PM: Message edited by: Ed MacLaren ]
These sketches that I have used in seminars might help supplement the good information above.
A "hole" is just a positively charged ion (atom that has lost an electron) which will accept a nearby free electron.
The free electrons that constitute current flow use the "holes" as "stepping stones" to move through the conductor material.
As a consequence of the movement of electrons from negative to positive, the holes can be seen to be moving from positive to negative.
Thus, the term "hole flow", sometimes used by the electronics industry to justify the conventional (positive to negative) theory of current flow, also still used in the automotive electrical field.
Ed
[ April 27, 2003, 10:29 PM: Message edited by: Ed MacLaren ]
charlie
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Re: electron flow
Some colleges and universities are still teaching "hole flow", such as Purdue University, because the guess as to the direction that electricity flowed was guessed incorrectly. After the advent of tubes (those glass thingies you see in museums that were before the transistor was invented), someone figured out that the actual electron flow was from negative to positive. Some institutions of higher learning were too stodgy to change so they taught hole flow.
The reason for just the Purdue University example is that is the only one I have knowledge of teaching "hole flow". I can only assume they still teach "hole flow".
Some colleges and universities are still teaching "hole flow", such as Purdue University, because the guess as to the direction that electricity flowed was guessed incorrectly. After the advent of tubes (those glass thingies you see in museums that were before the transistor was invented), someone figured out that the actual electron flow was from negative to positive. Some institutions of higher learning were too stodgy to change so they taught hole flow.
The reason for just the Purdue University example is that is the only one I have knowledge of teaching "hole flow". I can only assume they still teach "hole flow".
jxofaltrds
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Re: electron flow
I like the hole theory. It help explain why things move.
Ed's drawing A could be look at as a single 14awg.
Taking A and applying it to each line of drawing C is a good way to understand why a larger awg is needed to "move" electrons.
Could the hole theory help explain the dissipation of heat and why a wire will melt?
Mike P.
I like the hole theory. It help explain why things move.
Ed's drawing A could be look at as a single 14awg.
Taking A and applying it to each line of drawing C is a good way to understand why a larger awg is needed to "move" electrons.
Could the hole theory help explain the dissipation of heat and why a wire will melt?
Mike P.
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Re: electron flow
However, when I went into the Navy, all of the courses that I took and all of the circuits that I had to trace were set up for negative current.
When I attended Notre Dame and later attended the Illinois Institute of Technology, both schools taught current flow in terms of ?conventional current,? or ?hole flow.? They also taught us how to treat the same problems in terms of the flow of electrons, so that we knew what would be different and why it would be different. I believe that all EE programs will still teach this way.
However, when I went into the Navy, all of the courses that I took and all of the circuits that I had to trace were set up for negative current.
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Re: electron flow
Yes. Regardless of AC versus DC, regardless of voltage, and even regardless of current. Electrons move at (or I should say ?near?) the speed of light, as they travel around their host atoms, and when they jump from atom to atom. The difference between low current and high current is not the speed of electrons, but the number of electrons that are in motion.
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Re: electron flow
But there are gaps, HUGE gaps! Electrons travel around the center of atoms. At the center are the protons and neutrons. Suppose you hold a basketball, and consider that it represents the size of one proton. By relative size comparison, the electron would be about the size of a single grain of salt, and would be encircling you at a distance of about 15 miles! Your nearest neighbor atom will be at least 15 more miles beyond that point. There is a vast great deal of empty space inside even the most dense material known to mankind. But as to the use of the word ?holes? in the context of current flow, Ed has a good discussion.
bphgravity
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Re: electron flow
It is not perpetual motion. It is the law of attraction and repulsion. The electron is attrated to the proton, but because of the circular orbit, centrifical forces prevent it from ever coming in contact with the proton. Very similar to why Earth never crashes into the Sun.
It is not perpetual motion. It is the law of attraction and repulsion. The electron is attrated to the proton, but because of the circular orbit, centrifical forces prevent it from ever coming in contact with the proton. Very similar to why Earth never crashes into the Sun.
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Re: electron flow
This small scale world is so hard to comprehend, all this going on in everything around us!
Charlie, thank you for putting this in terms I can understand.
This small scale world is so hard to comprehend, all this going on in everything around us!
bphgravity
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Re: electron flow
I have seen another spectacular comparison to describe an electron in size. If the electron was increased to the size of a ping-ponf ball, the ping-pong ball would have to be increased to the size of the earth's orbit; 186,000,000 miles in diamter!!!
I have seen another spectacular comparison to describe an electron in size. If the electron was increased to the size of a ping-ponf ball, the ping-pong ball would have to be increased to the size of the earth's orbit; 186,000,000 miles in diamter!!!
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Re: electron flow
Bryan that is staggering, it is so hard to think in terms like that (for me anyway)
Do you know any analogies that help to describe how many atoms are in a given volume?
Bryan that is staggering, it is so hard to think in terms like that (for me anyway)
Do you know any analogies that help to describe how many atoms are in a given volume?
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