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Two Rays of Light

  1. Dec 30, 2007 #1
    When two rays of different colors of light cross each other what color is projected on the wall? Say for example, red light, and green light cross each other, what is the ultimate color projected on the wall? Why don't the colors get mixed up?
     
  2. jcsd
  3. Dec 30, 2007 #2

    Doc Al

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    Staff: Mentor

  4. Dec 30, 2007 #3
    why does this happen?
     
  5. Dec 30, 2007 #4

    Doc Al

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    It's a matter of the biology of color vision and how our three color receptors (cones) are stimulated. (If you're mainly interested in the biological aspects, I can move this thread to that forum.) There's a bit here: Wiki: Color vision
     
  6. Dec 30, 2007 #5

    DaveC426913

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    The colour(s) projected on the wall are (1) red and (2) green. Period.

    The human eye is sensitive to both read and green, but our brains interpret the combination of the two as yellow.
     
  7. Dec 31, 2007 #6
    Try this experiment: draw thin red lines alternated with thin green lines with bright colours on a bright white paper, then look at this drawing from some metres apart. You can do the same on computer monitor with a drawing application. The human eye cannot resolve the two different colours more than a certain limit, so the two colours signals will be mixed in your phisiological apparatus. This mixed signal is perceived as "yellow". The fact that a (really) yellow light is perceived in the same way, is due to the fact that yellow light has an average wavelenght between that of red and that of green light, so it will stimulate red receptors and green receptors in our eye in the same way.
     
    Last edited: Dec 31, 2007
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