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Absorbtion and Reflection of Objects, question

  1. Sep 20, 2009 #1
    I have a question which may be based in a complete misunderstanding of how "color" and our perception of it works in terms of objects absorbing certain wavelengths of light and reflecting a certain length to show that color.

    My question is why does an object reflect a specific wavelength versus another? To be cliche, why does a red apple reflect the wavelength that exhibits red to our eyes?

    What, on the object's surface, decides what is reflected or absorbed? Or is this altogether more dependent upon how our eyes work versus light and its being taken in by objects' surfaces?

    I'm not sure if I'm being clear. I've tried multiple different inputs into Google to try to find an answer but the information always is about how different wavelengths exhibit different colors and it depends on what the object reflects; but never why.

    Any insight is appreciated.
  2. jcsd
  3. Sep 20, 2009 #2
    It probably has to do with the energy levels of the material involved. If light of a particular frequency and hence photons of a particular energy matching the energy difference between a higher and lower energy level, then the atoms or electrons in the material would absorb these photons and transit to the higher energy level. Thus only specific frequencies of light corresponding to the energy differences are absorbed vis-a-vis the emission spectra phenomena.
  4. Sep 20, 2009 #3
    Hi cjahoda-
    The wavelength absorption band is too wide to represent transitions between bound atomic energy levels in individual atoms. The transitions would have to be between energy levels within valence or between valence bands.
    The light reflected off of colored surfaces, especially specular reflection off of shiney painted surfaces, is usually polarized, like for example Brewster's angle.
    Bob S
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