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Define the ampere

  1. Aug 25, 2010 #1
    1. The problem statement, all variables and given/known data
    Two very long, thin, straight, parallel wires each carrying a current I in the same direction are separated by a distance, d. With the aid of a diagram which indicates the current directions, account for the force on each wire and show on the diagram the direction of one of the forces. Write an expression for the magnitude of the force per unit length of wire and hence define the ampere.

    2. Relevant equations

    3. The attempt at a solution
    did necessary steps to get to force/length=uoI2/2pi*d
    then at 1m separation F=2*10-7I2
    From text: "if two long parallel wires 1m apart carry equal currents and experience a force of of 2*10-7N then the current is defined to be 1Ampere"
    I think im pretty close to the answer but I have a force of 2*10-7I2 -how do I get rid of the I2????
  2. jcsd
  3. Aug 25, 2010 #2


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    Homework Helper

    You are defining the Ampere, so I= 1 A.
  4. Aug 25, 2010 #3
    thanks I thought it would be something simple like that...
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