Function of the Electromagnetic spectrum

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Discussion Overview

The discussion revolves around the relationship between a mathematical function, specifically f(x) = sin(tan(log(x))), and the electromagnetic spectrum. Participants explore whether this function resembles the shape of the electromagnetic spectrum, which is often represented schematically. The conversation includes technical considerations of the spectrum's representation and its physical implications.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant proposes that their function f(x) = sin(tan(log(x))) may have a shape similar to the electromagnetic spectrum, referencing a specific image.
  • Another participant argues that the curve in the image is not a true representation of the electromagnetic spectrum, stating it lacks physical meaning and is merely a schematic.
  • It is suggested that the electromagnetic spectrum does not have a definitive shape, and the wavy representation is a visualization tool rather than a functional description.
  • A participant introduces the concept of a "chirp" function, indicating it may relate to the electromagnetic wave, but acknowledges its limited utility.
  • Further clarification is provided that while the chirp may visually resemble the proposed function, its spectrum does not match the electromagnetic spectrum as depicted.
  • Another participant discusses the relationship between wavelength and frequency, referencing the equation λ=c/f and noting that the diagram is exaggerated and not representative of physics.
  • Planck's Law is mentioned as the function that accurately describes the spectrum of electromagnetic radiation from an ideal hot body, emphasizing the peak amplitude's dependence on the emitter's temperature.

Areas of Agreement / Disagreement

Participants express differing views on the validity of correlating the proposed function with the electromagnetic spectrum. There is no consensus on whether the function accurately represents any aspect of the spectrum, and multiple competing interpretations of the spectrum's representation are present.

Contextual Notes

Participants highlight limitations in the schematic representation of the electromagnetic spectrum, including its lack of meaningful quantities along the axes and the exaggerated nature of the visualizations. The discussion also touches on the dependence of the chirp spectrum on its frequency distribution.

Gjmdp
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Hello. I was playing with functions one aftenoon until I got this one: f(x) = sin(tan(log(x))).
I was just wondering whether that function (at least, until the part that it doesn't get too compressed) has the same shape (to say it somehow) as the Electromagnetic spectrum.
https://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_compare_level1_lg.jpg
I think it does but I've been looking for many pages and none of them says anything about this function, or even a similar one.

Thanks
 
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The curve on the bottom of the image is not what people call "electromagnetic spectrum". It is just a schematic representation of how the wavelength changes. It has no physical meaning. There is no meaningful quantity along the horizontal axis so is not even a "function".
So I don't think you should waste your time in looking for some illusory correlation.
 
The electromagnetic spectrum doesn't have a shape. That wavy shape is just a way to communicate the fact that EM waves can span a wide range of wavelengths. It's just part of the visualization, and you are reading too much into it.
 
Gjmdp said:
Hello. I was playing with functions one aftenoon until I got this one: f(x) = sin(tan(log(x))).
I was just wondering whether that function (at least, until the part that it doesn't get too compressed) has the same shape (to say it somehow) as the Electromagnetic spectrum.
https://imagine.gsfc.nasa.gov/Images/science/EM_spectrum_compare_level1_lg.jpg
I think it does but I've been looking for many pages and none of them says anything about this function, or even a similar one.

Thanks
The function you are looking for is called a "chirp". There are different forms depending on the exact relationship between frequency and time.
 
Dale said:
The function you are looking for is called a "chirp". There are different forms depending on the exact relationship between frequency and time.
OK, thank you so much. It was exactly what I was looking for.

I know it has no much of utility, but I was just surprised that this rare function could ajust to this electromagnetic wave.
 
nasu said:
The curve on the bottom of the image is not what people call "electromagnetic spectrum". It is just a schematic representation of how the wavelength changes. It has no physical meaning. There is no meaningful quantity along the horizontal axis so is not even a "function".
So I don't think you should waste your time in looking for some illusory correlation.
Sure, now I've come to realize that. But there's something calle the "Chirp spectrum". I think it may have something to do with the electromagnetic wave.
 
The OP seems to be referring to an arbitrarily drawn diagram (commonly presented in order to 'help' people get the picture what's going on but there is the relationship
λ=c/f
where λ is the wavelength
c is the speed of light and
f is the frequency
That tells you that wavelength is inversely proportional to frequency so, allowing for the fact that 'that diagram' is grossly exaggerated, it sort of implies that a steady (linear) decrease in frequency of light would produce an inverse increase in the wavelength, which has a rough resemblance to that picture. But the picture is hardly anything but nonsense in terms of the Physics.
The function that really does describe the spectrum of the EM radiation from an ideal hot body is given by Planck's Law. That has a peak in amplitude that varies in wavelength according to the temperature of the emitter.
 

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