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Homework Help: Force on conductors

  1. Oct 18, 2007 #1
    Can someone tell me if im on the right track with this.

    Problem: Two parallel conductors are 15cm apart and carry current of 8 amp and 12 amp. Calculate the size and direction of the force that the conductors exert on each one meter length of each other.

    8 amp (out of page) o -------- 15cm --------- x (into page) 12 amp

    My attempt:
    Left conductor
    B=K x (i/d)
    B=2x10^-7 x (8/.15)
    B=1.06666 x 10^-5
    Right conductor
    B=K x (i/d)
    B=2x10^-7 x (12/.15)
    B=1.6 x 10^-5

    Since the currents are moving in opposite directions minus the smaller teslas from the larger.
    1.6x10^-5 - 1.06666 x 10^-5 = 5.3334 x 10^-6

    Only the 8amp conductor will experience a force.

    F=5.3334 x 10^-6 x 8 x 1
    = 4.26672 x 10^-5 N
  2. jcsd
  3. Oct 18, 2007 #2

    Doc Al

    User Avatar

    Staff: Mentor

    First find the magnetic field of one current at the location of the other. Then figure out the force per unit length on the current-carrying wire due to that magnetic field of the other wire. You only need to figure it out once, since the force on each will be equal and opposite.
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