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Find the direction and magnitude of the net magnetic field

  1. Mar 9, 2007 #1
    1. The problem statement, all variables and given/known data
    The two wires shown below carry currents of 5.00 A in opposite directions and are separated by 10.0 cm. Find the direction and magnitude of the net magnetic field a) at a point midway between the wires b) at point P1, 10.0 cm to the right of the wire on the right, and c) at point P2, 20.0 cm to the left of the wire on the left.

    2. Relevant equations
    B = uI/2(pi)r

    3. The attempt at a solution
    I got an answer for this, but I'm not sure because my instructor has never gone over vector addition in 3D nor in magnetism. Based on what I learned before, this is what I got
    a) 0. because both magnetic field are at the same magnitude but opposite direction. Therefore, their magnitudes cancel and the resultant is 0

    b) B = 1.26*10^-6*5.00/(2*3.14*0.1) = 1*10^-5T
    B = 1.26*10^-6*5.00/(2*3.16*0.2) = 5*10^-6T
    Bnet = 1*10^-5T - 5*10^-6T = 5*10^-6T out of the page
    c) B = 1.26*10^-6*5.00/(2*3.14*0.2) = 5*10^-6T
    B = 1.26*10^-6*5.00/(2*3.14*0.3) = 3.33*10^-6T
    Bnet = 5*10^-6 - 3.3*10^-6 = 1.7*10^-6T out of page

    Attached Files:

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    Last edited: Mar 10, 2007
  2. jcsd
  3. Mar 9, 2007 #2
    How did you get the direction of the field for part a?
  4. Mar 10, 2007 #3
    There's no direction because the two direction from the two wires cancel out. One is going into the page and another one is going out of the page
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