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Electromagnetic Spectrum

  1. Nov 9, 2011 #1
    What determines the wave length.
  2. jcsd
  3. Nov 9, 2011 #2


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    The length of the waves. Could you rephrase the question, please?
  4. Nov 9, 2011 #3
    The Lengths of the different waves and the frequencies are different such as gamma and microwaves being different.i understand how they are different but why
  5. Nov 9, 2011 #4
    The energy content of each photon is directly and rigorously related to that photon's wavelength and frequency. The governing equation is:


    All matter radiates electromagnetic energy. Each substance has allowable energy levels/wavelengths/frequencies at which it can radiate, and specific temperatures at which it can radiate them (its emission spectrum).

    From here on, it gets complicated.
  6. Nov 9, 2011 #5


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    Oh, are you asking why "microwave" and "radio wave" are defined by the particular frequencies they are?
  7. Nov 16, 2011 #6
    To my knowledge, what determines a wavelength is the frequency (the number of occurances of waves at a given point of time) of a wave. The wavelength is the distance between the troughs and peaks of a wave.

    I'd also like to note that the electromagnetic spectrum is made up of both visible, and invisble light, (Radio Waves, to visible light, to gamma rays), so we don't know which type of wave you are speaking of specificly.

    "The eternal mystery of the world is its comprehensibility." -Albert Einstein
  8. Nov 16, 2011 #7
    I guess if you trace it back, it is determined by the particle that emits it.
  9. Nov 16, 2011 #8


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    It doesn't matter which "type" of EM radiation you are referring to as all follow the same rules. The seperations between the types of EM Radiation is something we made, not something that actually exists. IE nothing special happens between the visibal and UV ranges, we simply put a line on our chart or graph or whatever and say "Here is where the visible ends and the UV begins."

    Also, set your quote up in your profile so it isn't quoted every time someone quotes you. :biggrin:
  10. Nov 28, 2011 #9


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    Just to elaborate on this a little bit:

    The frequency of EM emitted by any substance will jump to the next higher frequency (allowable for that substance) as energy increases. As an example, when we heat a piece of iron to higher and higher temperatures, the first result detectable by our senses is that the iron becomes hot. Heat is a relatively low EM frequency.

    As more energy is put into the iron, it begins to glow. This means that the iron is emitting higher EM frequencies, just entering the spectrum of "visible light", the lowest frequency of EM radiation visible to the human eye being the color red.

    If we continue to heat up iron, it will begin to glow orange, then the low, and eventually white (when colors from all across the visible spectrum are being emitted).
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