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Speed of light at an angle

  1. Oct 13, 2009 #1
    Let us say that an observer, O, saw a ray of light, such as a laser light (yellow curve), pass at an angle (omega). The speed of light would be constant in all frames, but wouldn't the observer record a relative speed of light c' = c*cos(omega) -- orange line -- assuming he/she couldn't tell the intensity decrease?

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    Last edited: Oct 13, 2009
  2. jcsd
  3. Oct 13, 2009 #2


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    c' is a component of the velocity. You get the velocity vector if you add the perpendicular component (which you omitted) to it. The length of this vector is called speed.
  4. Oct 13, 2009 #3
    Alright...Thanks for the reply.
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