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Speed of light in dispersive medium

  1. Aug 9, 2011 #1
    If light scatters when propagating through (example) water then why does it appear to travel in straight lines.

    Yes, i know pencils appear broken but the overall impression is of straight line focused light propagation, and that does not make sense to me from a 'scattering' point of view.

    If light does not scatter, then what slows it down?

    If it is due to absorption and emission, then why is the emission in the same direction as the absorption?

  2. jcsd
  3. Aug 9, 2011 #2


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    Staff Emeritus
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    Scattering is caused by the reflection of part of the light by non uniformities in the material. In glass of water there could be small bubble, impurities, or whatever that reflect part of the light in random directions. Only a small part of the light would be scattered in a glass of ordinary tap water, however one could add more impurities or blow bubbles with a straw and much more of the light would be scattered.

    The refraction of light is a different effect is is caused by the light moving from a material with a different refraction index than it was just in. It is not due to absorbtion and emission, but due to interaction of the EM waves with the material.
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