General > General Technical Chat
"Veritasium" (YT) - "The Big Misconception About Electricity" ?
HuronKing:
--- Quote from: penfold on February 14, 2022, 06:45:01 pm ---
--- Quote from: SandyCox on February 14, 2022, 06:27:25 pm ---
--- Quote from: penfold on February 14, 2022, 12:53:35 pm ---A thick enamel coating would affect the relationship between the external fields and internal charge density that would ultimately affect the speed of propagation. That is something that is probably most well studied in antenna theory, or at least if there were any surprising results, they'd have probably shown up in that field already... worth investigating maybe.
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The topic is not new. Here is an example of a paper:
https://ieeexplore.ieee.org/document/1131547
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And... hey presto... it is and it has been well studied in antennas... won't be purchasing the article, but I guess it's a safe assumption that from an input impedance and fields perspective it shows a good agreement with Maxwell?
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Absolutely - I can access these articles (hurrary for university login!) and I posted about this in this thread in reply #1019. The dielectric medium is very important and this is something predicted by Maxwell-Heaviside theory.
aetherist:
--- Quote from: SandyCox on February 14, 2022, 07:35:43 am ---
--- Quote from: aetherist on February 12, 2022, 10:08:29 am ---Either Pain is wrong or u is wrong.
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Is English your native language?
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If enuff of us say is & if is becomes the most common usage then is will become the correct grammar.
I have started the ball rolling but it are up to u to help.
TimFox:
Always remember that bad spelling and incorrect grammar is the usual method to detect spam.
adx:
aetherist, I had penned a reply which includes the above subject (insulation, slowing propagation) lastnight, something I meant to do a few pages back but ran out of time. It is only fair to explain, because it such a well-known result of conventional theory that it often taken for granted, which could leave you believing it is something new when it not.
But empirically so far you seem incapable of following through on a back and forth argument without branching off rapidly and repeatedly to familiar but different places like a fractal. I can understand that! Many on here can probably also relate to some degree, but there will be a limit to how much apparent contradiction or sales-job like attempts to dress up an ill-formed (incomplete) idea that they will swallow. FYI I am past that point, because you are either arguing with or persistently ignoring facts in a very unintelligent way.
But plug the dielectric constant into any online calculator which shows the per-length L and C of a transmission line. You will see that the C increases, but L does not. I don't need to explain (or understand) how that is. But simulate a pulse travelling through a lumped element transmission line, using your choice of cell size. The propagation speed of that pulse slows, a result of the per length increase in C, itself a result of the dielectric. This closely matches measurement.
Maybe there are some differences in the details that are as yet undiscovered, but that doesn't mean the scope traces and descriptions which show slowing of EM energy are grossly wrong.
Edit: Not changing anything, but not sure what took off those "'s"s, wasn't me AFAIK.
aetherist:
--- Quote from: penfold on February 14, 2022, 12:53:35 pm ---
--- Quote from: aetherist on February 14, 2022, 01:46:10 am ---[...]I don’t think that i have ever seen a calculation for the faux-speed of (old) electricity, but it would come out to about c/100,000,000.
The delay for a marble popping out would be at least as long as the delay of a sound wave in a glass marble.[...]
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How do you define the faux-speed? The change in charge distribution and current due to an electric field resulting from an injection of current or change in E-field or B-field is predicted rather well by Maxwell. Maxwell doesn't determine the electron velocities directly, only a J 'field', but it would be a pretty trivial step to determine how much charge is displaced and at what rate to satisfy the external E and B fields.
A thick enamel coating would affect the relationship between the external fields and internal charge density that would ultimately affect the speed of propagation. That is something that is probably most well studied in antenna theory, or at least if there were any surprising results, they'd have probably shown up in that field already... worth investigating maybe.
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Goodish equations that give goodish numbers is ok, but i have not seen any good (convincing) description of how enamel might affect the speed of electricity in/on/around a wire.
Re antennas -- my guess is that a transmitting dipole antenna painted with enamel would have to be 50% longer (to give the same frequency).
Re antennas -- no amount of so-called study can tell us the possible cause unless it looks deeply into the (microscopic) physics rather than the (macroscopic) maths.
I think that Maxwell did not need any encouragement to invent a mechanical model to help his thinking etc for whatever electrical problem that he was struggling with. So, if his writings didn’t include any such model for the effect of the insulation on a wire then it is safe to say that he was not even aware of the problem.
Heaviside too loved mechanical models for electricity, but here i think that his equations worked very well first pop, & hence he didn’t need a model for insulation. Or, he did have a model, but it was very simple, because it was basically a simple coaxial cable simply completely filled with simple insulation. Heaviside didn’t realise that he was also talking about (or should have been talking about) a simple wire with a simple thin coating of say shellac. Had he realised that a part of his energy current was in the shellac & that most of his energy current was outside the shellac, but that the thin layer of shellac won, then he would have been forced to make a complicated model, & his model might have lead to the discovery of the electon, & i would not be here writing my stuff today.
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