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EM Spectrum Continuous or Discrete?

  1. Nov 5, 2006 #1
    I have a question about the EM Spectrum. Is it existing in strips or is it completely continuos? Can a photon have a frequency of any value or does it have to have specific wavelengths according to the space between 2 electron orbits? I understand photons are generated when an electron drops from a higher to lower orbit in an atom. But i also understand that fission and fusion reactions can also generate photons. Just wondering if photons are limited in frequency value to the manufacturing process of them. Or can photons posses infinitely continuos values with limitless supply of decimal places describing their frequency or wavelength.

    Sincerely David Ong
  2. jcsd
  3. Nov 5, 2006 #2


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    It's continuous.
    The photons coming from atomic transitions are discrete, but there are other ways EM radiation can be produced.
    If you observe the spectrum from a fluorescent lamp for instance, you do see peaks at corresponding to atomic transitions but it's superposed on a continuous background radiation resulted from bremsstrahlung iirc.
  4. Nov 5, 2006 #3
    Another example is the continuous spectrum of a solid/liquid body. That of a light bulbe, e.g.
  5. Nov 5, 2006 #4
    In fact, even in systems where you would only expect photons at discrete wavelengths, you'll still find that they have finite linewidths (due to the energy-time uncertainty principle).
  6. Nov 6, 2006 #5
    the black body radiation continuous curve is, as far as i know, the sort of 'banging around' of electrons in, as a good example, a metal latice thus experiencing a whole bunch of different energy levels. you also find, i think, that due to the 'sea of electrons' in a metal you get many, many more energy levels other than the discrete ones defined by normal chemistry.
  7. Nov 6, 2006 #6
    does this mean that energy in nature is not strictly discrete because a photon can be generated to have any possible frequency and hence any possible energy value?
  8. Nov 6, 2006 #7
    Yes. The property of discrete energy states is a result of imposing boundary conditions on your wave equation, as one way of looking at it. The only time you see discrete states in quantum mechanics is if you are looking at bound states.
  9. Nov 6, 2006 #8
    does planck's constant also describes the area occupied by an entire wavelength of every possible photonic frequency in a time-energy graph?

    would that also mean that higher photonic frequencies have higher amplitudes while lower ones have smaller amplitudes?
    Last edited: Nov 7, 2006
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