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Homework Help: Calculating current in parallel wire

  1. Jul 16, 2011 #1
    1. The problem statement, all variables and given/known data

    A vertical straight wire carrying an upward 14.9A current exerts an attractive force per unit length of 8.50×10-4N/m on a second parallel wire 6.20cm away. What is the magnitude of the current that flows in the second wire?

    2. Relevant equations

    I2=2pir*F/I1*4pi e-7

    3. The attempt at a solution

    I2=2pi(.062)*8.5e-4/14.9*4pi e-7
    I2=2.7926e-11

    I keep getting ridiculous numbers and I can't figure out what I'm doing wrong...help?!
     
  2. jcsd
  3. Jul 16, 2011 #2
    I think you got your equation slightly off.
    Starting with F/[itex]\Delta[/itex]L=[itex]\mu[/itex]0I1I2/2pi*r, I ended up with
    I2=(F/[itex]\Delta[/itex]L)(2pi*r/[itex]\mu[/itex]0I1).
     
  4. Jul 17, 2011 #3
    Check your own arithmetic. The exponents indicate you screwed up the division.

    Do the basic checks before running for help.
     
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