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Homework Help: Finding the magnetic field at a point with two wires.

  1. Mar 23, 2012 #1
    1. The problem statement, all variables and given/known data
    Two parallel wires, each carrying a current of 2.2 A in the same direction, are shown in the figure . Find the magnitude of the net magnetic field at points A, B, and C.


    2. Relevant equations



    3. The attempt at a solution

    I believed I could simply calculate the magnetic field from each of the two wires then add up them up so

    B=(μ*2.2)/(2*pi*.075)= .000059

    B=(μ*2.2)/(2*pi*.225)= .000002

    Answer is in μT so I've tried 61, .000061, 57, ect.

    I know B is 0.
    Last edited: Mar 23, 2012
  2. jcsd
  3. Mar 23, 2012 #2


    User Avatar

    Staff: Mentor

    Magnetic fields are vector fields. That means they have directions as well as magnitudes. You need to take the field directions into account when you add them at a given point (vector addition). Do you recall learning about the right-hand rule for currents and magnetic fields?

    You might also consider using scientific notation for your values to avoid all those leading zeros and to manage appropriate significant figures in the values.
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