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Helium-neon Laser wavelength

  1. Feb 15, 2009 #1
    A helium-neon laser beam has a wavelength in air of 633nm. It takes 1.38 ns for the light to travel through 30cm of an unknown liquid.
    What is the wavelength of the laser beam in the liquid?
  2. jcsd
  3. Feb 15, 2009 #2


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    Gold Member

    How do you think you might be able to solve this? What are your thoughts?
  4. Feb 15, 2009 #3
    First i thought to solve for the index of refraction for the unknown liquid, by using n=c/v, but i think i need more info to solve it, thats were im stuck
  5. Feb 15, 2009 #4


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    You shouldn't need any more information. Look at what you are given. You have a time to travel a certain distance. What can you find with this information?
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