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Doppler effect of light

  1. Mar 14, 2009 #1
    I remember reading in a book that if we approached a red light
    really fast it would appear green to us due to the Doppler effect of light
    does any one know how fast we would need to travel for this to happen.
     
  2. jcsd
  3. Mar 14, 2009 #2
    If you are approaching a light source, then you can compute the shift in frequency of light by

    [tex]\nu_O=\nu_S\sqrt{\frac{1-v/c}{1+v/c}}[/tex]

    where [itex]\nu_O[/itex] is the frequency seen by the observer, [itex]\nu_S[/itex] is the frequency emitted by the source of the light, c is the speed of light, and v is the speed that you're traveling toward the source.
     
  4. Mar 14, 2009 #3
    sweet that helps , thank-you
     
  5. Mar 14, 2009 #4
    glad to help.
     
  6. Mar 14, 2009 #5
    The equation above seems to have a typo, because the equation says when source approaches the observer the freq decreases , which is wrong.
     
  7. Mar 14, 2009 #6
    Ah yes there is a typo--for approaching the signs should be reversed

    [tex]\nu_O=\nu_S\sqrt{\frac{1+v/c}{1-v/c}}[/tex]
     
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