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Homework Help: Force between two perpendicular currents

  1. Jul 25, 2010 #1
    1. The problem statement, all variables and given/known data

    Why is the force of a wire to another wire that is perpendicular to it zero?

    2. Relevant equations
    biot-savart law

    3. The attempt at a solution
  2. jcsd
  3. Jul 26, 2010 #2
    its because the magnetic field lines dut to one wire will be parallel to the another wire. And as the magnetic force is ilbsin(x) ad here the x is 0.
  4. Jul 26, 2010 #3
    the net force would be zero, but the net torque would not be. if you sketch this situation, and draw some field lines by one wire only (call it #2), you can use the RHR applied to wire #1, and because of #2's magnetic field, there would be a torque which would tend to make the two wires align parallel and carry current in the same direction.
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