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Veritasium "How Electricity Actually Works"

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aetherist:

--- Quote from: TimFox on May 10, 2022, 09:55:48 pm ---Fourier analysis shows that any periodic waveform can be represented as a series of sinusoidal waveforms, or an integral over a continuous frequency range of sinusoids.
When building a transmitter, you will find that a sinusoidal carrier is a useful and efficient generator of radio waves.
Even Marconi's evanescent waves from ratty spark waveforms contained a sinusoidal carrier, due to the resonance of the antenna system.
--- End quote ---
Yes i suppose that sinusoidal is best.
I am not sure how Hertz got a sinusoidal shape from his ordinary spark. I think that Ionel Dinu says that Hertz did not have a sinusoidal signal, ie it was faux-sinusoidal  (see other thread)(i haven’t read Ionel's papers lately).  If Hertz had a sinusoidal signal due to say resonance then Ionel Dinu would be wrong i think.

The Gasser-X was i think a version of Hertz-X, but mainly to do with speed. U might remember that Hertz had problems with speed, ie he got an infinite speed at one stage.  Here is some of Gasser's stuff, i haven’t read it lately, but it might have some interesting stuff. If not then i apologise.

Superluminal information transfer confirmed by simple experiment.
Wolfgang G. Gasser  (May, 2016).
Abstract:
A simple experiment has been performed in order to measure propagation speed of the electric field. The results show that the Coulomb interaction propagates substantially faster than at speed of light c.
Fig. 1:  Schematic of the experiment. [not shown]
The experiment uses a spark gap between two conducting spheres acting as capacitors of opposite electric charge. After spark-formation, this rapidly collapsing dipole field is measured by an oscilloscope connected via probes to conducting detector-spheres. Whereas the mutual distance between the detector spheres connected to the oscilloscope remains at Δx = 1.65 m (from left probe tip to right probe tip), different distances from the spark-gap have been measured.
Table. 1 [not shown]
The measured propagation speeds v = Δx/Δt from the left to the right detector sphere, with Δt averaged over each five measurements, range from around 1.4 c to 5 c, and show a dependence on the distance from the spark gap.

The by far simplest explanation of the experiment is the hypothesis that the Coulomb interaction conforms to Coulomb, who assumed instantaneous interaction at a distance. The dependence of the measured propagation speed on the distance of the measurement setup from the spark gap is explained by dissipative losses and "image charge" complication, leading to electric currents in the ground and the walls.
https://www.electronicspoint.com/forums/threads/experimental-evidence-for-v-c-in-case-of-coulomb-interaction.168813/
http://www.pandualism.com/c/coulomb_experiment.html

hamster_nz:

--- Quote from: Naej on May 10, 2022, 05:13:03 pm ---Sounds mostly correct to me. But I don't see how electrons are shoved by the electric field, with a stick perhaps? And how do they 'see' it, with tiny eyes?

--- End quote ---
I know how it is done in the math. Make a very small bounding box, add up the surface integrals to get net force. As the size of the box reduces to zero, the integral remains.

The physical reality? I do not know. But I can make something up.

Just perhaps the position of a charge is delocalized - it continuously randomly jumps around at very small scale (after all, charges to tunnel through potential energy barriers). Rather than being a point it is a small fuzzy thing (some magic quantum uncertainty handwaving).

When the electric field has a slope to it, that makes small jump with the gradient easier than a jump in the other which is against the gradient of the field. This bias allows energy to transfer from the field to the charge, and allows the charge to accelerate.

This is most likely not the process, but it is a nice easy (maybe even natural) process that could underly such a thing, avoiding the need for charges to have little eyes, little (or very long) sticks to push each other, backpacks to hold energy, and direct connections to all other charges in the universe. Instead they are all just bouncing on vanishingly small pogo sitcks  :-DD

TimFox:
"I am not sure how Hertz got a sinusoidal shape from his ordinary spark."

This is the same method Marconi used, exciting a resonant circuit (in Hertz' case, a "Hertzian dipole" resonant antenna) to generate an evanescent waveform:  a sine wave multiplied by a decaying exponential (as the circuit loss dissipates energy from the resonant circuit).  I believe the first practical transmitter to generate a true "continuous wave" was the Poulsen arc, later improved into the "Federal Arc", where a carbon arc's negative resistance placed across a resonant circuit.  Later, Alexandersson built a 200 kHz high-power alternator for GE.  Both were made obsolete by the vacuum tube.
https://farside.ph.utexas.edu/teaching/em/lectures/node94.html for the math behind the Hertzian dipole.

aetherist:

--- Quote from: TimFox on May 10, 2022, 11:38:36 pm ---"I am not sure how Hertz got a sinusoidal shape from his ordinary spark."
This is the same method Marconi used, exciting a resonant circuit (in Hertz' case, a "Hertzian dipole" resonant antenna) to generate an evanescent waveform:  a sine wave multiplied by a decaying exponential (as the circuit loss dissipates energy from the resonant circuit).  I believe the first practical transmitter to generate a true "continuous wave" was the Poulsen arc, later improved into the "Federal Arc", where a carbon arc's negative resistance placed across a resonant circuit.  Later, Alexandersson built a 200 kHz high-power alternator for GE.  Both were made obsolete by the vacuum tube.
https://farside.ph.utexas.edu/teaching/em/lectures/node94.html for the math behind the Hertzian dipole.
--- End quote ---
Interesting.
Anyhow, if Hertz intentionally or accidentally made a sinusoidal radio wave, then what reasoning was used by everyone to say that a radio wave is a photon(s).

TimFox:
See my reply no. 362 above.

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