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Homework Help: Stuck on math in deriving an optics equation

  1. Apr 17, 2010 #1
    1. The problem statement, all variables and given/known data

    Hi. For a project I have to derive this formula for bright fringes in optics, but i'm stuck on this simple math part (or maybe its not so simple)...ive attached a picture of where i don't understand...it might be considered a simple math problem so i'm sorry if this is too trivial a question for physics forums :)

    2. Relevant equations

    3. The attempt at a solution

    Attached Files:

  2. jcsd
  3. Apr 18, 2010 #2


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    Homework Helper

    (1+a)1/2 can be approximated by 1+a/2 if a<<1.

    For example:

    a=0.02: 1.021/2=1.00995...~1.01,

    a=0.002: 1.0021/2=1.0009995...~1.001

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