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What is the magnitude of the magnetic field .

  1. Apr 6, 2009 #1
    An overhead electric power line carries a maximum current of 165 A. What is the magnitude of the magnetic field at a point 2.40 m directly below the power line?

    Soo...
    I = 165A
    L = 2.40m

    Equations i have learnt areee
    (1) F = ILBsin(theta)
    (2) F = |q|vBsin(theta)
    (3) r = mv / |q|B
    (4) B = (constant)I/R

    im unsure
    . i tried equation 4 . but that didnt work. any help would be awesome!
     
  2. jcsd
  3. Apr 6, 2009 #2

    LowlyPion

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    Maybe this will help?
    http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html#c3
     
  4. Apr 6, 2009 #3
    i just tried it, and it doesnt work. :S
     
  5. Apr 6, 2009 #4

    LowlyPion

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    What units do they want it in? Gauss or Tesla?
     
  6. Apr 6, 2009 #5
    Tesla
     
  7. Apr 6, 2009 #6

    LowlyPion

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    What did you get then?
     
  8. Apr 6, 2009 #7
    i got two answers
    one was
    0.0000137T
    and
    0.0000275T
    Neither of them worked.
     
  9. Apr 6, 2009 #8

    LowlyPion

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    Is it looking for 1.38*10-5 T by any chance because of significant digits issues?
     
  10. Apr 6, 2009 #9
    ok, that worked :S:S
     
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