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How do i find the higher electric field of these two

  1. Mar 29, 2009 #1
    given a ball and an infinite pipe, both with the same radius and same charge density [tex]\sigma[/tex]
    what is the total electric field at the meeting point of the 2 if we bring them close together so that they touch at point A?

    what i did was:

    the ball has spherical symetry and the pipe has cylindrical symetry, so those are the shapes i will use for my gauss law,

    since RA=R

    for the ball
    [tex]\Phi[/tex]=EA=E(4[tex]\Pi[/tex]R2)=[tex]\sigma[/tex](4[tex]\Pi[/tex]R2)/[tex]\epsilon[/tex]0

    E=[tex]\sigma[/tex]/[tex]\epsilon[/tex]0

    for the pipe
    [tex]\Phi[/tex]=EA=E(2[tex]\Pi[/tex]R*L)=[tex]\sigma[/tex]2[tex]\Pi[/tex]R*L)/[tex]\epsilon[/tex]0

    E=[tex]\sigma[/tex]/[tex]\epsilon[/tex]0

    does this mean that the total field at point A will be 0 since they have the same field in opposite directions?
    does that make sense?
     
  2. jcsd
  3. Mar 29, 2009 #2

    Redbelly98

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    Looks right to me.
     
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