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Homework Help: Magnetic Fields and Maximum Current

  1. Mar 20, 2006 #1
    Hey guys I'm new here and needless to say I am completely lost...

    well here is the problem...

    What is the maximum current that a wire can carry if an experimenter is performing an experiment 0.60 m away that deals with the Earth's magnetic field (4.5*10-5 T), which she wishes to measure to +/- 1 percent?

    i thought I could just plug the #'s given into

    B = (4pi*10^-7)I / (2(pi)R)

    and i ended up with 135 A...which seemed muuuuuuuuch too high...and assumably was wrong....

    (4.5*10^-5) = (4pi*10^-7)I / 2(pi)(.6??)

    It would be greatly appreciated if i could get this help tonight...but I just want to understand what I'm doing wrong for the most part...
     
  2. jcsd
  3. Mar 20, 2006 #2
    well i found the error of my ways...

    the whole +/- 1% threw me off...

    i get the right answer if i multiply by the magnetic field by 1% and then re-plug everything in...

    hopefully this helps someone in the future...
     
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