General > General Technical Chat
"Veritasium" (YT) - "The Big Misconception About Electricity" ?
aetherist:
--- Quote from: TimFox on May 10, 2022, 07:53:01 pm ---With transmission lines, especially those of substantial length, the voltage and current are local, and don't include uncontrolled long wires outside the measurement.
Ideally, one defines a plane, perpendicular to the long direction of the coaxial cable (in this example) and the ideal voltage probe/oscilloscope measures the voltage from center to outer conductors in that plane, and the ideal current probe measures the current through the inner conductor passing through that plane.
Practical oscilloscope and current probes try to emulate that ideal situation.
When the diameter of the coax (again, in this example) becomes too large at the time scale of the measurement, we are crossing into waveguide territory, where we concentrate on the fields in the interior of the guide. Note that waveguides can be built with dielectric walls instead of conductive walls, with well-defined (in conventional electrodynamic theory) results similar to conductive guides, with the possibility of having a large DC (or lower-frequency than the waves) voltage from one end to the other. Similarly, if the interior of the waveguide is evacuated, one can run current in the form of electron or ion beams down the length of the guide, which will interact with the high-frequency fields. As mentioned in someone else's textbook citation, at the frequencies where waveguides are common, the skin depth in the metal walls is very small, and the energy is transported mainly in the traveling wave down the guide. With a bad termination, or a resonant cavity, energy can be stored in the standing wave.
There is a large literature and industrial history of both waveguides in general and particle accelerators in particular. Again, they both work.
When Heaviside made his huge breakthrough (realizing that adding lumped inductors in series with the telegraph lines improved their bandwidth), he may have used the telegraph system grounding as the return (bandwidth is not so high with manual Morse code). When AT&T successfully adopted his method to trunk telephone lines, they used twisted-pair transmission lines (balanced with respect to ground).
By the way, with respect to the outer insulation (jacket) on coaxial cables. I have used precision coaxial cables, some of which had armored jackets to prevent damage, and coaxial cables with various dielectrics (usually PE or PTFE), and various jackets (usually PVC), but also "semi-rigid" coaxial cables, where the outer conductor is essentially a copper tube, with no outer insulation. Careful use of these semi-rigid cables requires proper tooling for making bends, so as not to destroy the inner geometry. See https://www.pasternack.com/pages/Featured_Products/hand-formable-semi-rigid-cable-assemblies-up-to-18-ghz-new-from-pasternack.html?utm_campaign=usa_cable_assemblies&keyword=semi-rigid%20coaxial%20cable%20assemblies&gclid=eaiaiqobchmi2dv1-dzv9wivshrnch1uia-oeaayasaaegkoypd_bwe for such assemblies available with or without outer insulating jacket. Again, they work the same either way.
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Waveguides are another area where i know little, but i can smell a 2nd Nobel medallion.
Wires are a guide for electricity (elektons, ie photons). And wires can carry a flow of free surface electrons & drifting internal elektrons.
Waveguides are a guide for em radiation (radio waves)(radar).
It seems that em radiation (my photaenos) reflects off surfaces a bit like free photons (eg light) reflect.
I am worried about the term wave. E×H has no wave, it is a slab, all of the fancy perpendicular sinusoidal models are wrong.
However, the E×H can have a manmade wave, & hence yes the waveguide is a waveguide.
Wires carry photons, waveguides carry photaenos.
Naming em radiation photaenos aintgonnagetme a Nobel. I have to be patient.
Anyhow, i daresay that a waveguide has a Poynting Field inside. But here again i say that the Poynting Field duznt carry energy, it merely describes what is inside the waveguide. On the other hand i think that if we say that the Poynting Field carries the energy inside a waveguide then that kind of notion is fairly harmless, i don’t see it leading to a catastrophe down the track.
I suppose that i am ok with saying that in the Veritasium-X it is the Poynting Field that gives the induction that lights the bulb at 3.3 ns, but i aint ok with saying that it is the Poynting Field that carries the main electrical energy.
TimFox:
"I am worried about the term wave. E×H has no wave, it is a slab, all of the fancy perpendicular sinusoidal models are wrong."
What evidence do you have for the assertion that the fancy perpendicular sinusoidal models are wrong?
The fancy perpendicular sinusoidal models work well with traveling waves down waveguides and radiated waves propagating away from antennae.
Popular modes for waveguides are TE (transverse electric, where the E field component in the longitudinal direction of propagation is zero) and TM (transverse magnetic, the H component in the direction of proagation is zero.)
Arbitrary waves propagating in the longitudinal direction are superpositions of TE and TM, under normal conditions, and the transverse components of (time-dependent) E and H vectors are everywhere mutually perpendicular.
At this point, things get messy, and I don't claim expertise. Please refer to the standard textbooks on waveguides, and remember that WWII was won through use of radar, waveguides, magnetrons, and klystrons.
The finite conductivity of the walls in rectangular cross-section waveguides is a source of attenuation (loss) as energy propagates by the sinusoidal fields down the guide. When you see the mathematical equations, you will notice a spatial dependence in the transverse (cross-section) directions, and a sinusoidal time dependence down the longitudinal direction, with loss also in the longitudinal direction.
There is a cut-off frequency, below which the waves cannot propagate down a rectangular guide, which is why these rectangular pipes are used in the microwave frequency regime.
All of this stuff in the textbooks follows directly from Maxwell's equations. I admit that the mathematics is complicated.
aetherist:
--- Quote from: TimFox on May 10, 2022, 09:52:45 pm ---"I am worried about the term wave. E×H has no wave, it is a slab, all of the fancy perpendicular sinusoidal models are wrong."
What evidence do you have for the assertion that the fancy perpendicular sinusoidal models are wrong?
The fancy perpendicular sinusoidal models work well with traveling waves down waveguides and radiated waves propagating away from antennae.
Popular modes for waveguides are TE (transverse electric, where the E field component in the longitudinal direction of propagation is zero) and TM (transverse magnetic, the H component in the direction of propagation is zero.)
Arbitrary waves propagating in the longitudinal direction are superpositions of TE and TM, under normal conditions, and the transverse components of (time-dependent) E and H vectors are everywhere mutually perpendicular.
At this point, things get messy, and I don't claim expertise. Please refer to the standard textbooks on waveguides, and remember that WWII was won through use of radar, waveguides, magnetrons, and klystrons.
The finite conductivity of the walls in rectangular cross-section waveguides is a source of attenuation (loss) as energy propagates by the sinusoidal fields down the guide. When you see the mathematical equations, you will notice a spatial dependence in the transverse (cross-section) directions, and a sinusoidal time dependence down the longitudinal direction, with loss also in the longitudinal direction.
There is a cut-off frequency, below which the waves cannot propagate down a rectangular guide, which is why these rectangular pipes are used in the microwave frequency regime.
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Radar etc waves are manmade waves. They can be made to be sinusoidal or any shape we like. They are not the same animal as (non-manmade)(natural) Hertzian waves, which (if they existed)(which they don’t) would be sinusoidal all the time.
E and H are always perpendicular. In every theory.
They are perpendicular in Heaviside's transverse electromagnetic slab of energy current which makes his electric current (Heaviside is wrong)(electricity is my elektons, which emit his em slab).
They are perpendicular in the silly Hertzian rolling E by H by E theory.
There is no rolling E by H by E. The E & the H always go together, equal at all times.
However, if two H fields negate then we have a nett pure charge field.
If two E fields negate then we have a nett pure magnetic field.
Papers written by Ionel Dinu. https://www.gsjournal.net/Science-Journals-Papers/Author/111/Ionel,%20Dinu
Trouble with Maxwell's Electromagnetic Theory : Can Fields Induce Other Fields In Vacuum?
https://www.gsjournal.net/Science-Journals/Research%20Papers-Mechanics%20/%20Electrodynamics/Download/4219
Abstract -- The purpose of this article is to point out that Maxwell’s electromagnetic theory, believed by the majority of scientists a fundamental theory of physics, is in fact built on an unsupported assumption and on a faulty method of theoretical investigation. The result is that the whole theory cannot be considered reliable, nor its conclusions accurate descriptions of reality. In this work it is called into question whether radio waves (and light) travelling in vacuum, are indeed composed of mutually inducing electric & magnetic fields.
Radio Waves – Part IV : On the false Electric Waves of delusional Heinrich Hertz.
https://www.gsjournal.net/Science-Journals/Essays-Mechanics%20/%20Electrodynamics/Download/6248
Abstract -- After writing a paper critical to Maxwell’s electromagnetic theory, it is only natural to continue with an article critical to Hertz’s work. This is because every physics textbook today claims that Hertz demonstrated experimentally Maxwell’s theory. This claim amounts to saying that Hertz demonstrated experimentally that radio waves and light are electromagnetic, i.e. that they are made up of entangled electric and magnetic fields that oscillate and induce one another. In this work it will be shown that Hertz’s claim of having verified experimentally Maxwell’s theory is an exaggeration simply not true. Although Hertz did confirm the existence of a certain wave propagating in air, it cannot be said that his verification that the waves were composed of magnetic and electric oscillations is correct. And Hertz explicitly stated that he did not offer a direct verification that light itself is electromagnetic. I only wish more physicists read Hertz’s works before believing Maxwell’s theory or that it has been confirmed experimentally through Hertz’s works or otherwise.
Radio Waves – Part II.
https://www.gsjournal.net/Science-Journals/Research%20Papers-Mechanics%20/%20Electrodynamics/Download/4892
Abstract -- In Part I of this series on Radio Waves, I have tried to show that Maxwell’s theory of electromagnetic waves is untenable because electric fields cannot exist in vacuum where there are no electric charges to produce them and because experiments have yet to prove that electric fields can be produced in vacuum by changing magnetic fields. My aim was to show that a new theory of radio waves is needed since that based on Maxwell’s theory of electromagnetic waves claiming that a radio wave travelling in vacuum consists of oscillating electric and magnetic fields mutually inducing one another is not supported by experiments, being based on assumptions and mathematical manipulations.
Comments received from interested readers prompted me to offer further arguments against Maxwell’s theory and this led to an extended version of the same paper titled “Trouble with Maxwell’s Electromagnetic Theory: Can Fields Induce Other Fields in Vacuum?”. In this article I return to my original aim when I began this series on Radio Waves and I will try to show what I think radio waves really are and how are they produced in an antenna.
IanB:
--- Quote from: aetherist on May 10, 2022, 10:25:58 pm ---This is because every physics textbook today claims that Hertz demonstrated experimentally Maxwell’s theory.
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This is a general problem that comes up over and over again. Learning, understanding and education is not about reading textbooks as received wisdom and believing what they say. That is not science, that is religion.
Nobody knows what electrons, photons, electric fields, magnetic fields or electromagnetic radiation really are, and probably nobody can know. It is a pointless subject to argue about and serves no purpose.
What I do know is that people can design smartphones and computers and many other devices using established models of the world, and those devices work as intended. If our models were wrong, then all the engineers trying to design things would get very frustrated.
The way to make headway in a debate such as this is not to write lots of words and somehow think they convey meaning, because words are just words. You can make them say anything you like, but to what purpose? The way to make progress is to show that when people try to design computers, or telecommunications equipment, or silicon chips, that they fail, and that their designs do not work. Once you can show that, then you have evidence to claim that our model of the world is wrong and that we need new physics.
Berni:
--- Quote from: aetherist on May 10, 2022, 07:12:10 pm ---I suspect that the scope is its own ground. In any case ground is only a worry if voltage is critical, which here it aint, what we need is good nanoseconds not good nanovolts.
Re seeing a signal at all, that is old (electron) electricity. My new (electon) electricity don’t need no circuit.
Hence the X will confirm my electons whilst killing your electrons.
The electons are continuously circulating on the negative terminal of the lead acid battery. Fed from the electrolyte in the cell. They do not need any pumping or pushing. They merely need a contact, & off they go, at the speed of light (albeit slowed by the drag of the Cu surface)(ie the drag of the drifting electrons in the Cu)(plus a little bit of drag due to having to plough through free surface electrons).
Sweden here i kum.
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And why do you think there are more electrons on the negative terminal?
Because the battery is pumping them over from the positive terminal, this happenes until the battery cell voltage is reached. So if you take away the electrons on the negative terminal it will simply pump more electrons off the positive terminal to push it more positive. Even if you use the example of an electronically charged balloon, then you have a charged capacitor where one plate is the balloon and the other plate is the environment. As a result you can actually make the same balloon store more or less energy if you surround it with a different dielectric or not.
In the same way pushing a voltage into a scope probe without connecting the probe ground will simply push the entire scope to a higher potential and you see 0V on screen.
How much experience do you have in using an oscilloscope anyway?
--- Quote from: aetherist on May 10, 2022, 10:25:58 pm ---Radar etc waves are manmade waves. They can be made to be sinusoidal or any shape we like. They are not the same animal as (non-manmade)(natural) Hertzian waves, which (if they existed)(which they don’t) would be sinusoidal all the time.
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You can create any wave shape you want out of combining enough different frequency sinusoidal waves. This is well known for centuries now and used in many practical applications.
Feel free to apply the scientific method to your claims. Collect your assumptions on how electrons behave, use those assumptions to craft a prediction of how something might behave because of it, then finally use an experiment to verify that prediction.
As we have established using long enough pieces of wire makes it possible to measure these speeds without needing any super fast and expensive test equipment.
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