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Confused about light

  1. Apr 22, 2010 #1
    Confused about light!!

    Hello everyone,

    I'm confused about light. I know when a photon with certain matching energy comes, it excites the electrons to a higher orbital, and releases a photon when it comes back.

    1. What happens to the orginal photon that lost energy?
    2. I then read about absorption and reflection, then they were talking about resonance. I don't understand how what I described above with photons apply to reflection and absorption. Can anyone explain me to me with photon theory what happens in absorption and reflection.

    Thanks :smile:
  2. jcsd
  3. Apr 22, 2010 #2
    Re: Confused about light!!

    When a photon is absorbed by an electron, it disappears. You could think of it as the photon combines with the electron to create an excited electron.

    I'm not sure I understand your second question.
  4. Apr 22, 2010 #3


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    Re: Confused about light!!

    When you get reflection, a photon is not just interacting with one atom. The simple H atom is not an appropriate model to deal with EM wave interaction with a solid reflector. You don't get 'spectral lines' either by absorption or re-radiation in condensed matter, you get a broad band effect in which the energy of photons corresponding to a wide range of frequencies gets re-directed at the frequency of the original wave, in a 'specular' reflection. You can treat the process in terms of waves (it behaves classically).
  5. Apr 22, 2010 #4
    Re: Confused about light!!

    Thank you both for your replies :smile: They were helpful. I can understand the second question through waves. So my question basically is

    For reflection is this what happens or to understand reflection I have to consider light as a wave. If what I have quoted is not reflection what is it?

    Basically to understand reflection and absorption do I have to consider light as a wave?

    Thanks :smile:
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