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Homework Help: Wire with a Loop in it

  1. Feb 27, 2008 #1
    1. The problem statement, all variables and given/known data

    A very long wire carrying a conventional current of 4.8 amperes is straight except for a circular loop of radius 7.7 cm. Calculate the approximate magnitude of the magnetic field at the center of the loop.

    I know that I=4.8A and r = .077m
    u_o = 4*pi*(10^-7)

    2. Relevant equations

    3. The attempt at a solution

    I have everything and have been getting .0000392 T for the answer, but it's wrong.

    Please help! (ASAP Appreciated...) What am I doing wrong??
  2. jcsd
  3. Feb 27, 2008 #2

    Tom Mattson

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    Staff Emeritus
    Science Advisor
    Gold Member

    You calculated the field due to the loop current correctly. I think you need to add to that the contribution to the magnetic field that comes from the straight part of the wire.
  4. Feb 27, 2008 #3
    Yep, thanks a lot.
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