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Magnetic field by a finite section of wire?

  1. Apr 29, 2012 #1
    hey guys i have a question. i solved the problem but i dont understand how to do it.

    Two perpendicular straight wires join in the ends of a semicircular loop of radius a = 11 cm, as shown in the figure above. If the current I =6 A, what is the resultant field at the center of the circular section?


    i know how to get the magnetic field due to the semi circle, but for the two finite wires, i know from the integral we get uo I/ 4piR (sin phi1 + sinphi2). But for me when i look at each section of wire, I see the angles going from 0 to 90 degrees, so phi one is 0 degrees and phi 2 is 90 degree. Doing that gives 0. But that is obviously not right. Why do we use 45 degrees i just dont understand it? Please anyone!!
  2. jcsd
  3. Apr 29, 2012 #2


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    hi helpmeplz!! :smile:

    your picture is not visible (without logging in) :confused:

    can you please explain the shape (particularly the 45°)? :wink:
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