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Homework Help: Index of refraction and speed of light.

  1. Feb 28, 2009 #1
    Oh btw, this is not a homework question!!! just got it somewhere.
    Light travels in a medium of n=1.2 at c1. what is its speed in a medium of n=1.6?

    a)1.3c1
    b)0.67c1
    c)2c1
    d)1.7c1
    e)0.55c1

    my solution:
    using n=c/v, 1.2 = c/c1. also, 1.6=c/c2. c2= c/1.6. but c=1.2c1

    So, c2=(1.2/1.6) c1=0.75c1. but it isnt in the choices. any help? thanks

    also, do you know where i can find review materials for a-level physics (this is like UK based)? im preparing for university entrance exams. thanks!:>
     
  2. jcsd
  3. Feb 28, 2009 #2

    CompuChip

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    Your reasoning is correct, the answer should be 0.75 c1.
    Are you sure you copied all the numbers correctly?
     
  4. Feb 28, 2009 #3
    i'm so sure that's why i'm so confused. however, 1.6/1.2=1.3 and its in the choices.
     
  5. Feb 28, 2009 #4

    CompuChip

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    That's why I asked you to check the question.. if you'd interchange the 1.2 and 1.6, then the answer is there.
     
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