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Author Topic: Displacement Current - Does it Exist?  (Read 40221 times)

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It's not as complicated as it may seem...
Ivor Catt says no. Floyd Sweet endorses him.

The capacitor has been touted as a transmission line (Catt et al). This makes sense, at least to some degree.

.99
   
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Eric D used capacitors as transmission lines in LMD work
LMD - "Tesla transverse and longitudinal electric waves"
http://video.google.com/videoplay?docid=-721789270445596549#



[youtube]http://www.youtube.com/watch?v=4aLGkCp086s[/youtube]
« Last Edit: 2010-03-22, 05:51:09 by darkspeed »
   

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use a length of coax to set pulse width and you can see that it is a transmission line

the reflection turns off the pulse

Here is an interesting quote from Heavyside which Ivor Catt mentions:

Quote
The answer lies hidden in Heaviside's magnificent, regal statement, "We reverse this." In his Electrical Papers, vol. 1, 1892, page 438, Heaviside wrote;

Now, in Maxwell's theory there is the potential energy of the displacement produced in the dielectric parts by the electric force, and there is the kinetic or magnetic energy of the magnetic force in all parts of the field, including the conducting parts. They are supposed to be set up by the current in the wire. We reverse this; the current in the wire is set up by the energy transmitted through the medium around it….

The discrediting of displacement current merely makes Heaviside's "We reverse this" mandatory. It means that the field must be the cause and electric current an effect, rather than (as Maxwell thought) the other way round.

I have a very good paper somewhere where some gentlemen went to great lengths to prove this and succeeded in showing that the field does indeed cause electrons to drift.

EDIT:
Take a good look at a vacuum capacitor.  Electrons don't hop off the surface of one plate.  The space around the plate "changes" and this induces a change arond the other plate.  If you can create the right sort of "change" in the space around a conductor, you can make the electrons drift much like a continuously re-charged capacitor.  After all , this is all a magnet does when you move it across a conductor, see?

EDIT 2:
Found an old post I made on OU that is interesting:

http://74.125.155.132/search?q=cache:dBn2GM-Y67UJ:www.overunity.com/index.php%3Ftopic%3D8100.10%3Bimode+electrons+drift+displacement+grumpy&cd=1&hl=en&ct=clnk&gl=us

Here is the link to the paper that I mentioned above:

http://www.google.com/url?url=http://espace.library.uq.edu.au/eserv/UQ:9792/saha-edwards-aup.pdf&rct=j&sa=U&ei=vXi_SvL_JNLr_AaK74WCBQ&ct=res&cd=1&sig2=9ivonCUCUzWCr0BQKFcNew&q=electrons+current+diffuses+displacement+conductor+edwards&usg=AFQjCNECf3P_pak1lkQY7cvzDF3KwKKJDw


« Last Edit: 2010-03-22, 13:20:34 by Grumpy »
   

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It's not as complicated as it may seem...
« Last Edit: 2010-03-22, 13:58:17 by poynt99 »
   

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It's not as complicated as it may seem...
This all goes to the heart of electron flow in conductors (and between them); what it is, how it works, and if Maxwell was 100% correct.

All very interesting, and seemingly after all this time, we still don't know all there is to know about it.

.99
   
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I personally think more and more that electrons do not travel in a wire. They cannot. If electrons had mass, and if they traveled at the speeds indicated by regular knowledge, then they would have disintegrate all the mass in which they travel, regardless of the voltage/amperage. I have started to call the actual fact that power applied to one end of a wire reaching the other end and to a load as simply being "spin conveyance". I have not had enough time to develop this further into a real theory but in my next video I will be showing something pretty weird that will be able to show this is a general way. lol

Man that would be the top of top to actually discover that electrons in a wire receive a spin cadence from the source, then spin themselves throughout the wire to then convey that spin to the load or next component in the circuit. This explains so many effects that cannot be well explained both in our circuits, induction, sparks, lightning, you name it, it all hold together so well for me. If you Google "spin conveyance" you will only find one post i made a while back. lol

But maybe this is better left for the next generations.

wattsup
« Last Edit: 2010-03-22, 22:47:02 by wattsup »


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It's not as complicated as it may seem...
A couple references by Tombe about Maxwell's ID:

http://www.wbabin.net/science/tombe47.pdf
http://www.wbabin.net/science/tombe48.pdf

and a commentary on this by Ricker:
http://www.wbabin.net/science/ricker44.pdf

.99
   

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It's not as complicated as it may seem...
Wattsup,

It should be noted that there are two distinct velocities associated with electrons:

1) Drift Velocity - relatively slow and is actual "physical" propagation of electrons from one end to the other.

2) Velocity of EM propagation - approaches c, depending on permittivity and impedance etc. This is an apparent propagation of electrons, and is in reality a more or less "domino effect" (simplistic view) of electron movement transferred from one to the next, roughly in the direction of voltage polarization.

.99
   
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The way I see electrons is that they dont really move and if they do, not very fast.

However if you have a string of electrons in a material and induce a charge at one end the charge will propagate along the string of electrons much like a longitudinal wave.

When I visualize an electron I think of a spherical capacitor that can exist with or without a potential. When these spherical capacitors are in proximity of each other a charge when introduced will propagate along the string of capacitors. We are only moving the charge..

This is just my opinion
   

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It's not as complicated as it may seem...
Indeed DS, much along the lines of the simplified view I outlined above.

Drift velocity (actual electron flow) is quite slow. However the propagation of the "charge" is near c. Electron collision, or repulsion if you will, causes a ripple effect through the length of the conductor.

.99
   
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People equate electron flow to magnetic - and i think this is also wrong - I am conflicted on this one - but at times i think the magnetic field due to its speed may be some form of displacement due to charge velocity.

To visualize electron flow think of a pipe 3 meters in diameter with wet sand being pushed out at 1 cm per hour.. those grains of sand are electrons  ;D

   
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Indeed DS, much along the lines of the simplified view I outlined above.

Drift velocity (actual electron flow) is quite slow. However the propagation of the "charge" is near c. Electron collision, or repulsion if you will, causes a ripple effect through the length of the conductor.

.99

So electrons have an "Ambient" negative charge and then anything we add beyond that point they will propagate at <c
   

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It's not as complicated as it may seem...
Conduction Electrons

Some points gleaned from various sources:

1) In a vacuum the electric field would cause a charge to accelerate. In a wire, collisions of the conduction charges with impurities, imperfections, and vibrations of the atomic lattice causes the motion of the conduction charges to be slowed down. This represents a loss of energy which is dissipated as heat.

2) Within a metal conductor, even though there are free electrons, there is still resistance to current flow. This can be described by simple models, but apparently only quantum electron theories accurately deal with the behavior of metals under extreme conditions such as very low temperatures. Replacing the idea of electrons as particles with electrons as waves solves the problems of the simpler models. You can picture these electron waves oscillating through the metal lattice (which can also be pictured as a wave-like structure) - the interference of the lattice structure with the electrons causes resistance. This resistance is caused mainly by two things. One is impurities in the metal, which cause irregularities in the periodicity of the lattice. The other is the disturbance or "vibration" of the lattice caused by heat. Since some heat is always present (except at absolute zero) there is always some resistance from this source which prevents the electrons from sailing through.

3) The drift speed of electric charges

The mobile charged particles within a conductor move constantly in random directions. In order for a net flow of charge to exist, the particles must also move together with an average drift rate. Electrons are the charge carriers in metals and they follow an erratic path, bouncing from atom to atom, but generally drifting in the direction of the electric field. The speed at which they drift can be calculated from the equation:

    I=nAvQ  

where

    I  is the electric current
    n  is number of charged particles per unit volume
    A  is the cross-sectional area of the conductor
    v  is the drift velocity, and
    Q  is the charge on each particle.

Electric currents in solid matter are typically very slow flows. For example, in a copper wire of cross-section 0.5 mm², carrying a current of 5 A, the drift velocity of the electrons is of the order of a millimetre per second. To take a different example, in the near-vacuum inside a cathode ray tube, the electrons travel in near-straight lines ("ballistically") at about a tenth of the speed of light.

However, we know that electrical signals are electromagnetic waves which propagate at very high speed outside the surface of the conductor (moving at the speed of light, as can be deduced from Maxwell's Equations). For example, in AC power lines, the waves of electromagnetic energy propagate through the space between the wires which is usually filled with insulating material, moving from a source to a distant load, even though the electrons in the wires only move back and forth over a tiny distance. The velocity of the flowing charges is quite low. The associated electromagnetic energy travels at a speed which is much faster. The velocity factor is a measure of the speed of electromagnetic propagation compared to the speed of light in a vacuum. The velocity factor is affected by the nature of the insulating medium surrounding the conductor, and also the magnetic properties of the materials of the conductor and its surroundings.

The nature of these three velocities can be clarified by analogy with the three similar velocities associated with gases. The low drift velocity of charge carriers is analogous to air motions; to wind. The large signal velocity is roughly analogous to the rapid propagation of sound waves, while the large random motion of charges is analogous to heat; to the high thermal velocity of randomly vibrating gas particles.

4) Metals

Metals are good conductors of electricity and heat because they have unfilled space in the valence energy band. (The Fermi level dictates only partial occupancy of the band.) In the absence of an electric field, conduction electrons travel in all directions at very high velocities. Even at the coldest possible temperature — absolute zero — conduction electrons can still travel at the Fermi velocity (the velocity of electrons at the Fermi energy). When an electric field is applied, a slight imbalance develops and mobile electrons flow. Electrons in this band can be accelerated by the field because there are plenty of nearby unfilled states in the band.

Resistance comes about in a metal because of the scattering of electrons from defects in the lattice or by phonons. A crude classical theory of conduction in simple metals is the Drude model, in which scattering is characterized by a relaxation time τ. The conductivity is then given by the formula

    sigma = {ne^2 \tau}/{m}

where n is the density of conduction electrons, e is the electron charge, and m is the electron mass. A better model is the so-called semi-classical theory, in which the effect of the periodic potential of the lattice on the electrons gives them an effective mass (ref. band theory).

5) William Beaty's Speed of Electricity

6) In the classical model of electric conduction, a conductor (ie.
metal bar, wire, etc.) is pictured as a three dimensional array
of atoms or ions and the electrons are free to move about the
conductor.  In the absence of an electric field the elctrons
move about in the same manner as gas molecules move about in a
container.  The free electrons collide with ions of the 3-D
array and are in thermal equilibrium with them.  The speed
with which the electrons are "bouncing" around is on the order
of 10^7 cm/s.

When a potential electric field is applied, the electron
experiences a force and subsequently it is accelerated.  The
velocity of that electron is proportional to the force and the
duration that the force is applied.  It is inversely proportional
to the mass of the electron.

velocity = q * E * t / m

where q is the charge, E the field strength, t the duration, and
m the mass.  So in other words there is no "constant" speed for
electricity.

The net speed with which electrons travel under some field is
called the drift velocity. Here is an example of how to calculate
the drift velocity for electrons in a conductor carrying current:


example
-------
Say you have a piece of 14 gauge copper wire (radius 0.0814 cm)
and that wire is carrying 1 A.  We can assume one free electron
for every copper atom in the wire.  The density of free electrons
in the wire, n, is

n = (6.02 x 10^23 atoms/mol)(8.92 g/cc) / 63.5 g/mol

  = 8.46 x 10^22 atoms/cc

and the drift velocity, v, is

v = 1 C/s / (pi * 0.0814 cm * 0.0814 cm)(8.46x10^22 atoms/cc)(1.6x10^-19 C)

  = 3.55 x 10^-3 cm/s

  = 0.00255 cm/s

Note that this drift velocity is very small when compared to the
velocity the electron at thermal equilibrium is at "bouncing"
around.

[Moderator note:   Another way to look at this is from the perspective of an
electron.  For the wire mentioned above, when the current flows, it is just one
electron being pushed into the wire at one end, and another electron popping out
the other end, over and over many times a second.  The electrons in between
shift over with a speed of 0.00255 cm/s.  However, the speed of the "push" is
close to the speed of light, so that the electron on the far end of the wire
pops out very soon after the electron on the other end is pushed in. I think
your question brings up the additional question of what exactly electricity is.
Is it the electrons, or the movement of electrons?]


.99
« Last Edit: 2010-03-22, 20:27:48 by poynt99 »
   

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just change the properties fo the medium itself:

   
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Hi all,

Somewhat  charge related.

Take a glass jar which sits inside a metal container, close proximity. (leyden jar)

Take another metal container that fits inside the jar. Allow enough room for electrical seperation.

Charge the inner container with 30KV or more. The outer remains at earth potential throughout.

You can apply a grounded wire close to the inner and a spark appears...expected...

Charge the centre again but this time with insulated apparatus remove the central container.

Once clear you hold it in your hand so no charge exists on it.

Then place the container back inside the jar again with insulated apparatus.

With a grounded wire discharge the central container.......

Crazy or not a jar of electric with no wires...lol

Steve.





   

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It's not as complicated as it may seem...
Hi Steve.

There is an excellent video demonstrating this effect. I'll see if I can find it and post it here.

.99

[youtube]http://www.youtube.com/watch?v=9ckpQW9sdUg[/youtube]
   

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Excellent discussion.

In my experience: A capacitor is analogous to a TL in many ways. In both you can store a charge, dissect and reassemble with the same results as the previous Leyden jar video.

Maxwell does have his description of current flow backwards. Drift current is actual current flow. Apparent current flow is only the group velocity of drift current. Apparent current flow is what most folks think of as ‘current’.  Above all, any charge flow is in the dielectric.  

Keep in-mind most capacitors are an unterminated TL.


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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It's not as complicated as it may seem...
WW,

One of the burning questions I believe is: What if the dielectric is effectively removed?

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you can't remove the dielectric unless teh entire universe is a conductor
   

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you can't remove the dielectric unless teh entire universe is a conductor

Indeed!

I think that would require total non-existence. It exists at any point in space at varying impedance and is probably one of the properties of the so-called 'dark matter'.

(still living out of a suit case these days  >:( )


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"As far as the laws of mathematics refer to reality, they are not certain; as far as they are certain, they do not refer to reality." - Einstein

"What we observe is not nature itself, but nature exposed to our method of questioning." - Werner Heisenberg
   

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however, you CAN modulate the properties of the dielectric
   

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It's not as complicated as it may seem...
Answer the question guys... ::)

What if you removed the dielectric?

Would there still be a capacitor or TL?

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you can not remove all dielectrics from a conductor

air and vacuum is a dielectric, so no matter what you do, a conductor always has a dielectric around it
   
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I always viewed it as the electrons in metals were the charge carriers and the charge stored in the dielectrics is just THE CHARGE!

There are high potentials across most dielectrics just in room enviroment

The dielectric is the capacitor / the metal is the transport device

   

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we can probably detect the aether flow around a conductor when it is changing, but not when it's velocity is steady - might look like a propagating change in vacuum density

hang on - looking for some notes...
   
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