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Homework Help: Field due to a Current

  1. Feb 21, 2012 #1
    1. The problem statement, all variables and given/known data

    A current of 4.60 A is located at the origin, flowing along the z axis. (A positive current flows in the + k direction.) Find the magnetic field at the point (2.79,3.89) cm.

    Enter the x and y components of the field:

    2. Relevant equations

    B = μ[itex]_{°}(i)[/itex]/(2∏r)

    μ[itex]_{°}[/itex] = 4∏ x 10^-7

    3. The attempt at a solution

    used the Pythagorean theorem to find r = 0.04787

    used ampere's law to find B = 1.92x10^-5 T

    found θ at 54.35°

    from there i found

    Bx = Bcosθ = 1.12x10^-5 T
    By = Bsinθ = 1.56x10^-5 T

    not sure where i'm going wrong, thanks
  2. jcsd
  3. Feb 22, 2012 #2
    How did you find angle?
  4. Feb 22, 2012 #3
  5. Feb 22, 2012 #4
    George , what will be the direction of magnetic field at that point,?
  6. Feb 22, 2012 #5
    i'm not sure, i'm struggling with all this right hand rule stuff
  7. Feb 22, 2012 #6
    See , you need to know is ,
    The magnetic field will form concentric circles around the wire ,
    and the direction of magnetic field at any point will be the tangent of the circle at that point .
  8. Feb 22, 2012 #7
    This is the figure

    Attached Files:

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