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Homework Help: Net magnetic field

  1. May 4, 2005 #1
    I have a small question about net magnetic field.

    If I have 3 straight conductors that are parallel where
    -the current is to the left in conductor #3 (and situated at a distance b from #2)
    -the current is to the right in conductor #2. (and is situated at a distance a from #1)
    I have to find the net magnetic field exerted by #2 and #3 on the first conductor.


    Using RHR I found that:
    -conductor #3 , the magnetic field is directed out of the page;
    -Conductor #2, the magnetic field is into the page.


    To find the net magnetic field, should I use B= KI2/(b+a) - KI2/a

    Thank you in advance
     
    Last edited: May 4, 2005
  2. jcsd
  3. May 4, 2005 #2

    OlderDan

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    Are the conductors arranged in the order of number? #2 between #1 and #3? And was it supposed to say

    and

     
    Last edited: May 4, 2005
  4. May 4, 2005 #3
    Yes, it's supposed to say that. They are placed on top of the other.
     
  5. May 4, 2005 #4

    OlderDan

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    If I am reading it right, the denominator a+b should be b itself. Are you looking for just the magnetic field, or the force on wire #1?
     
  6. May 4, 2005 #5
    For the net B on wire #1

    -the current is to the left in conductor #3 (and situated at a distance b from #2)
    -the current is to the right in conductor #2. (and is situated at a distance a from #1)
     
  7. May 4, 2005 #6

    OlderDan

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    Then the b+a should be correct

    If #1 is on top, then your field directions are reversed. If #1 is on the bottom you have them right
     
  8. May 4, 2005 #7
    Yes, it is at the bottom

    Thank you
     
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