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Is there a reference of naturally occuring electromagnetic waves?

  1. Jan 31, 2010 #1
    I am interested in naturally occuring electromagnetic waves, is there a reference that lists wavelength, frequency, electric and magnetic fields, etc.?
     
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  3. Jan 31, 2010 #2

    russ_watters

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    Uh, well, there's the sun.....could you elaborate more on what you are looking for?
     
  4. Feb 1, 2010 #3
    NIST (National Institute of Science and Technology, formerly NBS) has a searchable database listing of atomic spectra lines and levels, listing the wavelength, energy, strength, and atomic source. See

    http://physics.nist.gov/PhysRefData/ASD/index.html

    For example, if you search for neutral sodium (Na I) lines between 5500 and 6000 Angstroms, you will find the two very strong yellow sodium doublet lines in sodium lights at 5889 and 5896 Angstroms.

    Bob S
     
  5. Feb 1, 2010 #4

    Redbelly98

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    Welcome to Physics Forums.

    I don't know if there is a list like that anywhere, but that doesn't prevent us from coming up with a list here.

    The sun (as Russ mentioned) and other stars.
    Pulsars.
    Quasars.
    Black holes.
    The cosmic microwave background.
    Thermal radiation from any object.
    Bioluminescence.
    Lightning.
     
  6. Feb 1, 2010 #5
    In college chemistry I used a reference, tables of standard values for solutions. I was wondering if there was a similar reference, tables of standard values for electromagnetic waves.
    I am hoping that looking at the table I can get a better mental image of the relationships of wavelength, frequency,amplitude, etc..
    I realize that man can produce electromagnetic waves, mojulate them and otherwise alter their properties, so I have limited my search to naturally occuring electromagnetic waves.

    Thanks
    MOMc
     
  7. Feb 1, 2010 #6

    Redbelly98

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    The relationship between frequency and wavelength is
    f = c/λ​
    This relationship holds for both natural and man-made radiation, whatever the source. It is shown graphically here, along with the photon energy:
    http://www.electrical-res.com/EX/10-17-19/SURA_Electromagnetic_Spectrum_Full_Chart.jpg

    The amplitude or intensity of the radiation would depend on the nature of the source and your distance from it. I've never hear of any all-encompassing compilation as you are asking for. I guess you would probably have to pick a few examples and do some research or ask questions about specific cases.
     
  8. Feb 2, 2010 #7

    QuantumPion

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    Why do they list sound waves and ultrasound on that chart under low frequency electromagnetic waves? :grumpy:
     
  9. Feb 2, 2010 #8
    I looked at www.physics.nist[/URL] and other similar sites and found the information interesting but overwhelming. As you point out below, others have already formulated these relationships.

    [quote="Redbelly98, post: 2559086"]The relationship between frequency and wavelength is
    [INDENT]f = c/λ[/INDENT]
    This relationship holds for both natural and man-made radiation, whatever the source. It is shown graphically here, along with the photon energy:
    [url]http://www.electrical-res.com/EX/10-17-19/SURA_Electromagnetic_Spectrum_Full_Chart.jpg[/url]

    The amplitude or intensity of the radiation would depend on the nature of the source and your distance from it. I've never hear of any all-encompassing compilation as you are asking for. I guess you would probably have to pick a few examples and do some research or ask questions about specific cases.[/QUOTE]

    frequency = c x wavelength.
    and total kenetic energy of a photon is = h x frequency

    In a box at the bottom of the chart at [url]www.electrical-res.com[/url] is the following:
    wavelength = 3x10to the 10/frequency = 1.24x10 to the -6 /eV

    what is the 1.24x10 to the -6 / eV? The kenetic energy of the photon? The stregth of the electricfield? ???

    thanks again

    MOM
     
    Last edited by a moderator: Apr 24, 2017
  10. Feb 2, 2010 #9

    Born2bwire

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    That would be the energy of the photon. I do agree with QuantumPion, the inclusion of sound waves is rather egregious.
     
  11. Feb 2, 2010 #10
    a 12,398 Angstrom wavelength photon is a 1 eV photon. a 1.2398 x 10-6 meter wavelength photon is a 1 eV photon. Visible light is from ~4,000 to about 6,500 Angstroms (2 to 3 eV).

    Bob S
     
  12. Feb 3, 2010 #11

    Redbelly98

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    Why do you think that? The frequency is c divided by wavelength, as I said before.

    Whoah, missed that. :uhh: Sound waves shouldn't even fit on their frequency scale (> 105 Hz)
     
  13. Feb 3, 2010 #12
    I really want to thank you all for your help.

    Sorry! New computer, new operating system,trying to figure out how to get math symbols into e-mail, therefore, head not truly engaged while typing. Frequency= c divided by wavelength.

    I agree that sound should not be included in this scale.

    How are the electric and magnetic fields related to frequency,wavelength,energy of the photon?
     
  14. Feb 3, 2010 #13

    turin

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    The chart refers to them as "Sources and Uses of Frequency Bands", not as types of EM waves. Anyway, my stereo generates electrical signals at 10's of kHz, and the ultrasound machine also uses electronics to generate the ultrasound frequencies, so there are EM waves that are directly related to sound.
     
  15. Feb 3, 2010 #14

    Redbelly98

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    Technically, you could say the electric and magnetic field strength depend on the volume occupied by the photon, which would be different depending on the specific situation. In practice, electric and magnetic field strength are useful when talking about E-M waves classically, and not so useful when treating E-M fields as discrete photons.
     
  16. Feb 4, 2010 #15
    Could you be more specific and or suggest some sites where I could get more information about E-M fields.

    thanks, MOM
     
  17. Feb 4, 2010 #16

    Redbelly98

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    Not really. So far you have asked pretty general questions, so the answers must be general.
    That depends on how much physics you already know. I can take a guess, and suggest the text book Physics: Principles With Applications by Giancoli. It covers electricity, magnetism, and optics at a basic level.

    https://www.amazon.com/Physics-Prin...=sr_1_7?ie=UTF8&s=books&qid=1265339687&sr=8-7
     
    Last edited by a moderator: May 4, 2017
  18. Feb 5, 2010 #17
    Thanks. I took a year of college [classical] physics and a couple years of college calculus in the sixties. Later I became an MD. Now I'm retired and trying to understand some of the basics that underly our universe. Somewhere physics took a right turn and took off. I'm trying to catch up. Asking general questions that lead to more and more specific questions. I've needed a new text book. Thank you for your recomendation.

    Looking at your previous replies there seems to be a disconnect between the wavelength, freqency and the keinetic energy of E-M waves and their electric and magnetic fields. I am not completely surprized by the disconnect and I am very interested in how it is resolved.

    You said the electro and magnetic field strength had to do with the volume occupied by the photon and varied under different situations. Interesting. The field strength varies repeatedly from zero to max and back to zero. But I suspect there is more. Under what situations do the field strengths vary. Does the volume of the photon vary and this gives rise to the repeating variable field strengths?

    My fantasy is that photons represent packets of energy, quanta [gamma>radio].
    They have an inertial mass and velocity> kinetic energy. Their trejectories are bent by gravity. etc.
    Here is the disconnect.
    They have an inherient energy [gamma>radio] apart from their kenetic energy.
    It is this inherent energy that is responcible for the electro and magnetic fields.
    The gamma fields are greater than those of radio.
    Thanks,MOM
     
    Last edited by a moderator: May 4, 2017
  19. Feb 5, 2010 #18

    turin

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    One thing to note is that the number of photons does not commute with the phase of the EM field.[1] This is a QM notion, and it is basically a version of the Heisenberg uncertainty principle. What it means is that you cannot specify the existence of a (single) photon and the shape of the EM field (location of peaks and troughs) simulatneously.

    The justification may be over your head. But, if you can accept the Heisenberg uncertainty principle, just think of it that way.

    ------------------------------------------------------------------------

    [1] See, for instance, J. J. Sakurai, Advanced Quantum Mechanics, 10th ed., 1984, pp. 32-35. See especially eq. (2.89).
     
  20. Feb 6, 2010 #19

    Redbelly98

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    It sounds like the Giancoli book will be a good place to learn (or relearn) the basics. It uses algebra and trigonometry--no getting around that if you want to learn physics--but not calculus. I've seen it used for high school honors physics, as well as college physics for non physics majors.

    Best to first review the basics of E-M fields and also oscillations & waves, which are all covered in the Giancoli book. I'll just note that physicists refer to the energy of a photon. It is not considered kinetic energy, which is the energy of motion of a massive object.

    You're describing the oscillation of the field strength. The photon volume would usually not change during an oscillation cycle, but is determined by for example any mirrors or obstructions that are present. Or the photon may not be confined to a volume at all in some cases, for example an atom emitting a photon into free space.

    That is pretty much the definition of what a photon is.
    I have never heard of anyone talking about the "inertial mass" of a photon. But yes, their trajectories are bent by gravity. That gets into the realm of general relativity, not my area of expertise.

    Well, that's sounding pretty speculative, i.e. outside the mainstream view, which means off-limits in terms of our forum guidelines of discussion. We're here to teach, learn, and discuss mainstream science. I take your comments as an attempt to learn about photons and E-M fields, so that's okay.

    I have had a similar problem with thermodynamics, in particular heat engines. A year or so ago I took some time to learn the very basics, and just yesterday bit the bullet and ordered a recommended textbook so that I can spend the time and effort to learn more of the details. I love that there are used, discounted copies of textbooks easily available online.
     
  21. Feb 8, 2010 #20
    Thanks

    I'm going to take your advice and do some reading and see if I can understand the mainstream view better.

    Old school physics pointed out that the rest mass of a photon was zero but as a moving object the photon had an inertial mass.

    Thanks again, MOM
     
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