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Homework Help: Find Magnitude of Magnetic Field Along Bent Wire at Point P

  1. Oct 23, 2012 #1
    1. The problem statement, all variables and given/known data
    A wire carrying a 31.0 A current bends through a right angle. Consider two 2.00 mm segments of wire, each 3.00 cm from the bend. A figure has been included.

    Part A) Find the magnitude of the magnetic field these two segments produce at point P, which is midway between them.

    Part B) Find the direction of the magnetic field at point P.

    2. Relevant equations

    [itex]\vec{}B[/itex] = μ0*I*Lsin(θ)/4∏r2

    3. The attempt at a solution

    Using the calculation given above:

    B = (10^-7)(31A)(2/1000 m)sin(45)/(18/400)
    B = 9.74x10^-8

    However there are two wires thus, B = 1.948x10^-7

    But it says my answer is wrong and I can't pinpoint where I'm going wrong.

    Also, for part B, I'm a little confused about the direction the magnetic field is acting in. Is the force of the magnetic field acting pointing towards point P thus indicating that the magnetic field is point out of the page?

    Attached Files:

  2. jcsd
  3. Oct 23, 2012 #2


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    Homework Helper
    Gold Member
    2017 Award

    Did you square the r in the denominator when you were doing the calculation?

    I don't understand your reasoning for the direction of B. But the direction is not out of the page. See if your text or notes explains how to get the direction.
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