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Homework Help: Force between identical wires in a circuit (1st post)

  1. Dec 9, 2009 #1
    1. Two Identical wires denoted A & B are part of an electric circuit and therefore carry some currents. The wires are characterized by resistance per unit length,r, and both have length, L, each are spaced by a distance, a. What is the magnitude, F, of the force the wires exert on each other? Is this force an attractive force? For the given resistance, R of the resistor, what should be the length, L, to achieve maximum possible, F,?

    Equations i thought might be useful..:
    E=I*((r*L/2) + R)

    My attempt:


    I =emf/2rL+R

    emf=I*((r*L/2) + R)

    Then the force is equal to length, by current, by magnetic field. Because the current is going in the same direction in the two wires it will be an attraction force.

    When you get Force as a function of L,
    F = (µ0 *E^2)/(2*pi*a*r^2*L) where
    pi = 3.141592....

    Im unsure if this is even right, and where I go from here.. all help is appreciated..
  2. jcsd
  3. Dec 9, 2009 #2
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