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Optics - Rainbow

  1. Mar 22, 2008 #1
    1. A man stands on a mountain peak 2 km from the ground below, and observes a rainbow 8 km away. What fraction of the arc of the rainbow does the man see?

    2. Relevant equations

    I tried using a triangle to figure this out but I couldn't come any closer to the answer.
    I know that the rainbow largely depends on the rain drop where red has a larger angle of deviation than violet allowing one to see red on top rather than on the bottom. Red is 42 degrees while violet is 40 degrees, etc. etc. The rest of the colors are in between more or less. Understanding this doesn't seem to help me figure it out :(

    3. The attempt at a solution

    No idea. The teacher gave us the answer, .586 , but that really doesn't help me understand the problem. Please help. Thanks!
    Last edited: Mar 22, 2008
  2. jcsd
  3. Mar 22, 2008 #2


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    Hi Skynt! :smile:

    Don't we need to know the height of the sun? :confused:
  4. Mar 22, 2008 #3
    Well, this problem came from the book - and I agree, that came to my mind as well. The teacher said we didn't need it.
  5. Mar 23, 2008 #4


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    Well. unless I'm missing something, the teacher is wrong - see:

    hmm … the question doesn't say "at a beautiful sunset", does it? :smile:
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