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Gauss's law on a charged sheet.

  1. Apr 22, 2014 #1
    1. The problem statement, all variables and given/known data

    find the field produced by a uniformly charged sheet carrying 87 pC/m2

    2. Relevant equations

    [itex]\oint \vec{E}.d\vec{A}[/itex] = qenclosed/[itex]\epsilon[/itex]

    3. The attempt at a solution

    [itex]\Phi[/itex]= [itex]\sigma[/itex]A/[itex]\epsilon[/itex]
    [itex]\Phi[/itex]=[itex]\oint E.dA[/itex] = ## E(2A) ##

    2EA= [itex]\sigma[/itex]A/[itex]\epsilon[/itex]
    E = [itex]\sigma[/itex]/(2[itex]\epsilon[/itex]) = 4.92 N/C where I use 8.85*10-12 for [itex]\epsilon[/itex] (this has been the value used through the book)
    However the book says the answer is 49 kN/C
    could someone point out my error? Thanks.
     
  2. jcsd
  3. Apr 22, 2014 #2

    Doc Al

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    Staff: Mentor

    Your answer looks OK to me. What book are you using?
     
  4. Apr 22, 2014 #3

    Doc Al

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    Staff: Mentor

    Since you are off (from the book's answer) by 104, I wonder if the charge density was meant to be in pC/cm2, not pC/m2.
     
  5. Apr 22, 2014 #4
    I'm using Richard Wolfson's: essential university physics 2nd edition, ch 21 qn 33.
     
  6. Apr 22, 2014 #5
    yeah that might be the problem, as i have seen similar qns to this one online but they use pC/cm^2 instead of pC/m^2
     
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