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Find the Current using Force/Length Between Two Wires

  1. Aug 2, 2012 #1
    1. The problem statement, all variables and given/known data
    Two long parallel wires are separated by .006 m. The current in one of the wires is twice the other current. If the magnitude of the force on a 3m length of one of the wires is equal to 8μN, what is the greater of the two currents?

    The answer: .40 A

    2. Relevant equations
    F/L = (μ0)(Ia)(Ib) / 2∏d
    μ0 = 4∏x10^-7
    d = distance between the wires
    Ia/b = values for the two currents

    3. The attempt at a solution
    I plugged everything in like so: (8x10^-6)/3 = (4∏x10^-7)(I)(2I)/2∏(.06)
    From that, I divided the left side and the right, leaving me with:
    2.67x10^-6 = 3.33x10^-6(2I^2)
    Then I just solved for I by getting I by itself (.801/2 = I^2) and and taking the square root of (.801/2) to find I. At this point, I've found that I = .63A , but I don't know where to go from here. The answer should come out to be .40A.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Aug 2, 2012 #2

    rude man

    User Avatar
    Homework Helper
    Gold Member

    The problem says d = 0.006m but you used d = 0.06m
     
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