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Homework Help: Electric Field at Point question

  1. Oct 4, 2006 #1
  2. jcsd
  3. Oct 4, 2006 #2

    Doc Al

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    Your answer and work look OK to me.
     
  4. Oct 4, 2006 #3
    Thx, my confidence doesn't feel so shattered now :P
     
  5. Oct 4, 2006 #4

    Doc Al

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    Though your work was just fine, you could save yourself some effort by using a symmetry argument.
     
  6. Oct 4, 2006 #5
    Teacher just got back to me... turns the side of the square is A...somehow looking at how they depicted A in that drawing made me think A was the distance from center... even though it says in the instructions that A is the whole side... zzz

    using distance from center = a/2 then problem comes out to their answer 3.05e13
     
  7. Oct 4, 2006 #6

    Doc Al

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    D'oh! Sorry about that... I must have been sleeping also. (I just looked at the diagram and ASSumed that "a" was the distance from the origin.) :frown:
     
  8. Oct 4, 2006 #7
    It's ok...this problem was booby trapped! :cry:
     
  9. Oct 5, 2006 #8
    o quick question...

    is the unit vector R always in direction from the charge to the point..QP
     
  10. Oct 5, 2006 #9

    Doc Al

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    Yes, if you mean in the expression for the field at point P due to charge Q:
    [tex]\vec{E} = \frac{k Q}{R^2} \hat{R}[/tex]
     
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