I will reply to comments below on this page, in order to keep the dialog in one place

Some inspiration for you. Do you see the loop of current propagating down the TL?

Constant314 ( talk) 21:11, 27 April 2023 (UTC) reply

Sure -- Chetvorno ^TALK 14:46, 2 May 2023 (UTC) reply

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Hi, I see you're good at physics. May I ask for your help on the Geiger-Marsden experiments article?

Talk:Geiger-Marsden experiments

I want to know if I got my maths right with this one. I haven't done physics since high school, I'm rather rusty. Kurzon ( talk) 14:46, 13 June 2023 (UTC) reply

There was an IPv6 who reverted some obvious vandalism. I have reverted it again. T3h 1337 b0y 21:54, 3 July 2023 (UTC) reply

@ T3h 1337 b0y: My bad. I was in a hurry and mistakenly read the diff backwards, thought he had added the vandalism. Thanks for letting me know. -- Chetvorno ^TALK 15:45, 4 July 2023 (UTC) reply

Good idea with that repositioning! I was trying to figure out why the caption you added for File:Early triode vacuum tubes.jpg was "bottom to top" (D-C-B-A) for the image, until I realized it was approximately chronological order, starting from the main article topic. Would it be a more natural reading order if the rows of the image itself were ordered with the oldest at top? I can do it if you think so. DMacks ( talk) 18:34, 5 September 2023 (UTC) reply

That's a good idea, the existing photo is awkward. I thought the picture was of a museum cabinet with 4 shelves, but on closer look it seems to be a composite of 4 separate photos anyway. I'd say go ahead. Maybe relabel the rows too, so the Audions are A? Thanks. -- Chetvorno ^TALK 03:50, 6 September 2023 (UTC) reply

You recently made some additions to the entry "Grimeton Radio Station". The current text has some technical errors, the "Schematic diagram of principles" is very generic and not Grimeton specific and sources are missing.

I have created a new description in the German Wiki in the section "Technische Beschreibung" using historical sources. I would like to integrate this also in the English text. However, I am a German speaker. I can create a first version with the help of DeepL. But this would have to be proofread and corrected by an english speaking person. Do you want to help? JoergLuzern ( talk) 12:18, 29 October 2023 (UTC) reply

New: My text is now also available on the english wiki. Could you check my English? (In the German wiki there is a mandatory check before publication, seems not to be the case here ;-)). — Preceding unsigned comment added by JoergLuzern ( talk • contribs) 09:25, 31 October 2023 (UTC) reply

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I believe far field radiation corresponds to the radiation carried by what is usually referred to as electromagnetic radiation, light, radio waves etc. The reason it diminishes with 1/r in earth based situations is because we do not use spherical transmitters like the sun. Instead our transmitters generally have a straight axis. Therefore the radiation spreads like a cylindrical section rather than a spherical one so that changes in distance only impact one dimension rather than two . Our drawing in the two articles electromagnetic field and electromagnetic radiation is deficient because it shows waves which do not decrease with distance -- a case only applicable to photons.

The near field radiation deserves a good drawing as well. This radiation is caused mainly by the charges which move back and forth directly. Unlike far field the max velocity magnetic peak occurs at the same time as the minimum electrical field. So unlike the drawing the peaks are perfectly offset. It would have a drawing where the magnetic and the electric field peaks are offset and fall away much faster with distance.

Do you agree that the oscillating field drawing on both articles is incorrect showing either a laser or photons which do not diminish with 1/r? Bill field pulse ( talk) 19:38, 28 January 2024 (UTC) reply

I agree with some of your points, but not that the drawing should be changed:

• The fields of electromagnetic waves sufficiently far from the source decrease with ${\displaystyle 1/r}$ not because they spread cylindrically, but because energy is conserved. In order for the total amount of power striking the surface of a spherical shell enclosing the source to be constant regardless of radius ${\displaystyle r}$ (a definition of conservation of radiated energy), the power density ${\displaystyle S}$ of the radiation must decrease with the inverse square ${\displaystyle 1/r^{2}}$ of the radius (because the area increases with the square of radius ${\displaystyle r^{2}}$). The power density is proportional to the square of the fields: ${\displaystyle S={\epsilon _{0}c \over 2}E_{p}^{2}}$ so far from the source the peak electric and magnetic fields of electromagnetic waves must decrease linearly, as ${\displaystyle 1/r}$ with distance from the source. They decrease at that rate whether on Earth or in space.
• The "near field radiation" is not radiation. The near fields of a radiating antenna or atom look pretty much like ordinary dipole electric and magnetic fields that are oscillating. You can see what the electric fields of a radiating dipole antenna look like in this gif animation I made. I agree it would be useful to have a drawing, preferably an animation, of the near fields.
• I agree far from the source the amplitude of the fields of an electromagnetic wave in free space decrease with ${\displaystyle 1/r}$, but in most of the far field the decrease is too small to see in a drawing. The drawing Onde electromagnetique.svg you are complaining about shows about 2 wavelengths of an electromagnetic wave. As an example, a radio wave from a 300 MHz television station has a wavelength of 1 meter. At a distance of 1 kilometer, the decrease in amplitude of the electric and magnetic field over the 2 wavelengths from one end of the drawing to the other would be only a factor of ${\displaystyle 1-{1000-2 \over 1000}=}$ 0.002 = 0.2%. This would be completely imperceptible in the drawing. A light beam from a red laser pointer has a wavelength of 650 nm. Ten centimeters from the laser the decrease factor would be only ${\displaystyle 1-{0.1-2*0.00000065 \over 0.1}=}$ 0.00013 = 0.013%. Far field radiation is usually approximated as a plane wave, a flat wavefront with the fields as constant amplitude sine waves similar to that in the drawing. I think it would be confusing to show a drawing of the fields with the amplitude decreasing, as that would only be an accurate representation of the fields near the source.

-- Chetvorno ^TALK 00:39, 30 January 2024 (UTC) reply

1) I see that my assumption that radiation amplitude and the power density at a point is wrong for the far field. Is it just a coincidence that amplitude and power density drop equally in the near field with r squared? So it is just like the sun where the total power in a thin spherical shell is constant and the radiation decreases with r squared. I imagined that maybe with a radio transmitter the geometry impacted the power drop. For example, with a laser the power drop is reduced because all the radiation is aligned and there is less diffusion with distance.

2) I completely agree that the near fields must be exactly like the normal fields around charges in this case oscillating. I also do not like to refer to these inner fields as "electromagnetic radiation" preferring to restrict that term to the radiation involving photons. However, do you agree that if a charge moves quickly the field is not infinitely rigid but establishes around the charge from the charge first on outward at the speed of light. This is still very, very rigid much more rigid than macro objects -- like a steel ball -- which establish around fixed points less quickly due to stretch of molecules etc. If you agree with this then around near light speed quarks the establishing from the center out is equivalent to "radiating" and EM field must be flexible and for quarks a field intensity wake must result.

If you have a good drawing of the near field I support you putting it in to the article. It would help people see that the field around charges is always there. I have not yet looked at your animation but I will look at it soon.

3) I think the drawing must say "looking far from the source". If we are looking at the first two 1 meter wavelengths then the second one should be half the amplitude of first one. I think a drawing was taken from a photon lecture. I like a slight change in amplitude rather than the appearance of constant amplitude. Bill field pulse ( talk) 20:44, 30 January 2024 (UTC) reply

Your animation is excellent for the far field and better in some ways than the one we are using.

Your animation clearly shows a near spherical spread. I have seen others drawings where there is a frontal lobe of less than 45 degree spread and a smaller rearward lobe also less than 45 degrees. The radiation power in other directions was far lower in the practical examples I saw. I guess designers can direct the far field to minimize power waste depending where they want the most power to go. Bill field pulse ( talk) 20:57, 30 January 2024 (UTC) reply

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Thanks for catching all my spelling errors--danger of late-night editing w/o LanguageTools turned on! DrKC MD ( talk) 18:48, 6 April 2024 (UTC) reply

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