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Question about light's speed

  1. Jun 17, 2004 #1
    how does air/glass/water slow down light?
  2. jcsd
  3. Jun 17, 2004 #2
    It doesn't really.. light speed remains the same. However, photons are absorbed and re-emitted on the way through the medium and it is the time that this takes that makes them appear to travel slower.
  4. Jun 18, 2004 #3
    Why are they absorbed and re-emitted? How?
  5. Jun 18, 2004 #4
    Basically photons carry a certain amount of energy with them. Electrons bound to an atom (not free electrons) will be able to absorb this energy and fly up an energy level or two. When they go back down they will emit a photon.

    Question, does the index of refraction reflect colors of different wavelengths differently because the latice structure of the compound? Also, how come there is no light that goes straight, or is there just a tiny amount due to probability of not being scattered.
  6. Jun 18, 2004 #5


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    Light moves "straight" through a vacuum.
  7. Jun 18, 2004 #6
    Why is it then re-emitted in the same (or opposite, whatever you want) direction that it has been absorbed?
  8. Jun 18, 2004 #7


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    Conservation of momentum.
  9. Jun 18, 2004 #8


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