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Homework Help: Magnetic field of an infinite wire

  1. Feb 21, 2009 #1
    1. The problem statement, all variables and given/known data

    Hey guys.
    So I've got a current which goes through an infinite wire and I need to find the magnetic field which is caused by the wire at point P.
    I used the Biot–Savart Law and in the picture you can see what I came up with (sorry, no scanner today, I had to do it the short way :smile:).
    So, my question is, how am I suppose to get from the green equation to the red one? I took the red equation from their answers.
    Am I missing something?

    Thanks.


    2. Relevant equations



    3. The attempt at a solution
     

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  3. Feb 21, 2009 #2

    Hootenanny

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    You might want to recheck the Green equation, it seems that you did not integrate correctly.
     
  4. Feb 21, 2009 #3
    Ops, my bag, how am I suppose to integrate it? :blushing:
     
  5. Feb 21, 2009 #4

    Hootenanny

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    No problem. That integral looks almost like a standard integral and can be evaluated using the same substitution as you would use for the standard integral... :wink:
     
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