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Homework Help: When finding Magnetic Field between two wires

  1. Jul 17, 2014 #1
    1. The problem statement, all variables and given/known data
    11. Two parallel conductors, 1.0 cm apart, each carry 10 A of current in opposite directions. What is the magnetic field strength at the midpoint between these wires?

    2. Relevant equations

    B = μI/ 2πr

    3. The attempt at a solution

    I know that the magnetic field is doubled because the currents are in opposite directions.

    Should r = 0.01 m or 0.005 m?

    Is the r the distance between the two wires? I thought that r is the perpendicular distance from the wire to the point of field measurement, so that would mean 0.005 m.

    I think the answer in my book is wrong, because it has r = 0.01 m.

    Please advise.
  2. jcsd
  3. Jul 17, 2014 #2


    User Avatar
    Homework Helper
    Gold Member
    2017 Award

    Hi, mistermill.

    You are correct. r is the perpendicular distance from the wire to the field point. So, r = .005 m for each current.
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