You talk about the dielectric, while I talk about what happens INSIDE the plates.
Here: https://electronics.stackexchange.com/questions/532541/is-the-electric-field-in-a-wire-constant
I put some references in this answer. A good deal of that is freely available on the net. Try to read at least the essay by Chabay and Sherwood.
I detect a continuing love affair around here for lumped element transmission line models. I wish to point out that there has never been any good correlation tween such a model & experiment for a DC transient of the Veritasium gedanken kind, albeit using 1000 m of Cu (AlphaPhoenix) or 22 m of Cu (Veritasium) or 8 ft of Cu (Howardlong) or any m or ft of Cu.
Q6. Why did the yellow trace start its main rise at 63.0 ns, when the speed of electricity along the 21 m Cu tube (10 m out plus 1 m spacing plus 10 m back) is 3.34 ns/m in air which demands that the rise should have been at 70.1 ns? A delay of 63.0 ns suggests a tube Cu length of only 18.9 m (2.1 m too short). Q6A. Why was the speed of electricity 10% faster than c?
re Q6: With all the complaints about the speed of light, has anyone included the meter of probe cable? Or its velocity factor? Just wondering...
re Q6. I have not looked at the graph that closely and I do not know their exact setup and how accurate their length measurements where. But is also irrelevant.
Funny, the link opens fine on my side. Maybe local servers undergo maintenance at different times.
Yes, inside the plates means inside the wires and inside the resistor.
Your simplification is assuming a lot of things that are true in circuit theory but are not necessarily true in the physical systems we are considering. Wait for the site to go back online.
[electrodacus] Veritasium says almost zero about the exact lengths, but i think that the total L of Cu tubing is 42 m.
I like the way that Veritasium has the tubing say 2.5 m above the ground, so that ground reflexions don’t spoil his measurement of the 3.3 ns delay. And then he duznt even show us (on his scope screen) where exactly we can see his measurement of his 3.3 ns delay.
Veritasium duznt tell us whether the Cu tubing has an enamel coating. We all know that the speed of electricity drops from c/1 down to 2c/3 when a Cu tubing is painted or when it is insulated.
Which brings me to my main point today. Duz a lumped element transmission line model allow input for the insulation on a wire?
Duz a lumped element transmission line model allow for ground reflexion?
Veritasium made much of Ben Watson's lumped element transmission line model. Actually i think that it was not a lumped element transmission line model, i think that it might have been a direct application of Maxwell. Duzzenmadder. The same question arises. Duz his Maxwell TL model allow input for the insulation on a wire?
I do not think there is any enamel of the copper pipe (that will not be common as far as I know). Also even if there was a thin layer of enamel or paint it will not charge the capacitance in any significant way as there is about 1m of air in between.
Also even if capacitance was some other value (say closer pipes or anything like that it will still be irrelevant for the main question).
The transmission line model is very accurate and just a digitization of the real transmission line as you need finite element's in order to do the calculation.
So as mentioned the setup can be simplified to just a charged capacitor (in place of the battery or power supply) and a discharged capacitor that is paralleled to the charged capacitor to approximate the transmission line and even the load.
You can have the two discharged series capacitors with a resistor in the middle but since the resistor is just a wire with higher resistance is not needed and since two series capacitors are the same with a single half capacity capacitor the simplification is perfectly accurate to explain the fact that all energy from one capacitor to the other is transferred trough wires (capacitor plates are also wires).
When you connect a charged capacitor to a discharged capacitor you have two ideal capacitors in series with a resistance (ESR) so the charge capacitor is say at 20V and discharged capacitor at 0V then 20V is the drop on the series resistance ESR plus is you want a light bulb Voltage will drop on the charged capacitor as it is discharged while the voltage on the discharged capacitor increases. The current is limited by the series resistance ESR plus lamp if you want to have one there.
There is no electric field in the discharged capacitor and the field is only present when there is a delta in electrons on the two plates.
The electric field has nothing to do with the energy transfer as that is done by electrons trough the wire and the electric field is the consequence of the electron imbalance. No electron imbalance no electric field.
Nah, the antennae successfully worked, and the capacitors charged as predicted.
Looks to me like another win for Maxwell's equations, but you are free to give a participation trophy to Poynting instead.
Veritasium duznt tell us whether the Cu tubing has an enamel coating. We all know that the speed of electricity drops from c/1 down to 2c/3 when a Cu tubing is painted or when it is insulated.
Which brings me to my main point today. Duz a lumped element transmission line model allow input for the insulation on a wire?
Duz a lumped element transmission line model allow for ground reflexion?
Veritasium duznt tell us whether the Cu tubing has an enamel coating. We all know that the speed of electricity drops from c/1 down to 2c/3 when a Cu tubing is painted or when it is insulated.
Which brings me to my main point today. Duz a lumped element transmission line model allow input for the insulation on a wire?
Duz a lumped element transmission line model allow for ground reflexion?Your rule of thumb for the enamel affect on the speed is only approximate for very closely spaced wires, such as a twisted pair transmission line. The effect is due to the storage of charge in the dielectric, where the field pulls all the electrons slightly in one direction, they then release and create a new field. The speed results from the superposition of the source and self generated field. (Aware that the theory I describe is also only a model and there is likely a quantum explanation for it)
When you have large amounts of air in between the superposition is dominated by the field in the air. Hence speed is very close to C.
You can create a lumped element model that accounts for ground reflection, but it would be horrible. I think OpenEMS pretty much does this for it's FDTD EM simulations.
The 2/3c velocity factor is only a rule of thumb!
Here are the velocity factors for some of the common coax cables:
https://www.febo.com/reference/cable_data.html
The PE insulated version of RG6 (cable TV cable) or the classical RG58 is indeed 2/3c (66% speed of light) but there are lots of other cable types that are significantly faster than that. This is because they separate the conductors using different dielectric materials or even just use the same dielectric material in a different physical layout (such as foam or hollow grid)
Simply enamel coating a wire does not put a magical 2/3c speed limit on those electrons! You would need to cast both wires into a solid block of enamel resin for it to have this drastic of an effect on the velocity factor. If you have mostly air between the conductors the velocity factor is mostly determined by dielectric properties of air.
Nah, the antennae successfully worked, and the capacitors charged as predicted.
Exactly. That's why I said that invoking antennas and, now, capacitors won't save your claim. These two devices show that energy resides in the fields present outside their respective conductors.
QuoteLooks to me like another win for Maxwell's equations, but you are free to give a participation trophy to Poynting instead.Oh yeah. All of them are winners: Maxwell, Heaviside, Poynting, you name it. What they predicted Nature confirmed, saving us to have to give ears to "influencers" and crackpots.
Those charts go as low as VF 66 which is 2c/3. The higher VFs for some cables are due to air (foam).
But, they are i think for coax. Veritasium & AlphaPhoenix & Co are all using plain wire (with enamel) or plain tubing (no enamel).
I am fairly sure that a thin coating of enamel gives a VF of 66 (for wire or tube). And that thicker coatings give a VF of 66. And that a mile thick coating would give a VF of 66.
At some extreme thinness (say 0.001 mm)(enamel) the VF might start to rise. And would go to 100 at zero enamel.
U would think that this stuff would have been done to death by now.
Re a VF of 66 for a tube with enamel. I meant enamel on the outside. But it raises the question of what the VF would be for (a) enamel on the outside, or (b) enamel on the inside, or (c) enamel on both inside & outside, & of course (d) no enamel.
Those charts go as low as VF 66 which is 2c/3. The higher VFs for some cables are due to air (foam).
But, they are i think for coax. Veritasium & AlphaPhoenix & Co are all using plain wire (with enamel) or plain tubing (no enamel).
I am fairly sure that a thin coating of enamel gives a VF of 66 (for wire or tube). And that thicker coatings give a VF of 66. And that a mile thick coating would give a VF of 66.
At some extreme thinness (say 0.001 mm)(enamel) the VF might start to rise. And would go to 100 at zero enamel.
U would think that this stuff would have been done to death by now.
Re a VF of 66 for a tube with enamel. I meant enamel on the outside. But it raises the question of what the VF would be for (a) enamel on the outside, or (b) enamel on the inside, or (c) enamel on both inside & outside, & of course (d) no enamel.So at what thickness does the enamel change the propagation speed from 1c to 2/3c? 1 atom thick? 100 atoms? 10um? 100um? 1mm? Copper oxide is also a dielectric, so do signals also travel slower trough heavily oxidized copper wires?
Here you can find a table of the velocity factor for twin line cables made by Wireman:
https://www.dj0ip.de/open-wire-fed-ant/openwire-info/
As you can see the velocity factor from the table is 0.91, making it even faster than the fast types of coax. Yet the copper wires are surrounded by insulation, so why is it faster than coax? The reason is that most of the volume between the conductors is air (This is why they are useful, as air is low loss).
The equation for velocity factor is this:
So it shows that the speed is only determined by the relative permeability of the insulator. When you mix different insulators you get a permeability somewhere in between. When the wire is insulated on the surface with plastic and then separated by air then you get a permeability somewhere in between plastic and air, the more plastic you have the closer the permeability will be to plastic. In the case of twin line transmission lines yes there is plastic all the way between (since that is what holds the wires the correct distance apart) but the electric field doesn't just go straight, it also curves around, taking a path that is mostly trough air.
So by your logic if you build a capacitor from two 1cm separated metal plates, then put a thin plastic foil on each plate you expect to get the same result as if there was a 1cm solid block of plastic between the plates. This is not the case. The capacitor with the thick block of plastic will have a higher capacitance since the average dielectric permeability of the space between the plates is higher.
EDIT: Fixed link
Hontas Farmer is back
I'm not sure what claim it is supposed to save, but these devices illustrate that electrons can push on electrons outside their conductor. To absolutely no one's surprise.
They do not, in any way, prove that energy resides in the vacuum; and indeed anyone can check that neither you nor Derek gave any proof of this (it does not exist, it cannot exist).
It's a win for Maxwell's equations, but if you want to attribute it to Poynting, Plato or Derek, well I'm a bit puzzled but why not.
Hontas Farmer is back
Hontas Farmer is back
Derek addresses her misconception about how electrons behave inside a wire from 2:36 to 15:01 in his second video. She forgot to account for the nuclei of the atoms, with which they also interact and have opposite charge. Something that I pointed out myself when commenting about the first video.
Derek even showed that statistically (which is something she likes to invoke) the net effect of the interactions between the electrons themselves and the nuclei is zero.
The rest of her video is pseudo-scientific tactic 101: a quote from Feynman out of context here and there and the showing of books no one will read because they will not understand anyway.
Her dismissal of classical electrodynamics is also misleading: at the macroscopic level QED and CED converge as shown by Feynman in his description of the Aharonov-Bohm effect, about which I also commented pages ago along this thread. This means that for this experiment CED is good enough.
What I find amusing is that she says that Derek is "probably" wrong, as if he were a subatomic particle.
A quantitative discussion of the effect of normal insulation layers on velocity factor in antenna construction:
https://lowpowerlab.com/guide/rf-best-practices/velocity-factor/
Summary:
0.95 for bare copper wires
additional factor of 0.95 to 0.98 when adding normal insulating materials (PVC, polyethylene, PTFE)
These factors are important when calculating antenna length.
To get down to 0.66, you need a coaxial construction such as RG-58/U with solid polyethylene dielectric
With RG-62A/U, which has an internal construction which is roughly half air and half polyethylene (annular geometry), the characteristic impedance rises to 93 ohms, and the velocity factor is 0.83.
Foamy dielectrics have similar velocity factors.
I'm not sure what claim it is supposed to save, but these devices illustrate that electrons can push on electrons outside their conductor. To absolutely no one's surprise.Yeah. How do they do that? Do they have little arms to shove their fellow creatures one meter away?QuoteThey do not, in any way, prove that energy resides in the vacuum; and indeed anyone can check that neither you nor Derek gave any proof of this (it does not exist, it cannot exist).How is the energy for the push transferred from one electron to another through the "vacuum" 1 meter away? Do they throw stones at each other?
QuoteIt's a win for Maxwell's equations, but if you want to attribute it to Poynting, Plato or Derek, well I'm a bit puzzled but why not.It's a win for nature, that dismantled the wires-are-pipes stupidity.
There's nothing more absurd than looking at physics equations and say "how?", it's not a religion, it's an axiom.
"Natural" antennae dismantled what? You think people who know that wires are pipes never heard of antennae?