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Homework Help: Find y-component of Electric Field!

  1. Feb 12, 2012 #1
    1. The problem statement, all variables and given/known data

    A plane of charge lies in the xz-plane at the origin. Its surface charge density is =4.57 uC/m^2; other charges are present in the vicinity as well. Just to the right of the origin the y-component of the electric field is 520,000N/C. What is the y-component of the electric field just to the left of the origin. Answer must take into account direction of field (left negative, right positive).

    Eright = 520000
    σ = 4.57 uC/m^2

    2. Relevant equations

    Enet = σ/ 2 ε0
    Enet = Eright + Eleft

    3. The attempt at a solution

    I started with Enet = σ/ 2 ε0 = 258070
    Eright = 520000
    so via Algebra, Eleft = -261930

    The sum of Eleft and Eright should be 258070,
    what am I doing wrong?

    Last edited: Feb 12, 2012
  2. jcsd
  3. Feb 13, 2012 #2


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    Homework Helper

    yo, erik welcome to physicsforums

    I don't really understand the question. There is a plane of charge in the xz plane, going through the origin. OK, and just to the right of the origin, the y-component of the electric field is 520,000N/C I'm guessing that means the y direction is to the right?

    You've got the equation Enet = σ/ 2 ε0 I don't know why you've called it Enet, because this equation tells you the magnitude of the electric field on either side of a plane of charge.

    And you've got roughly the right answer for σ/ 2 ε0 = 258070 the magnitude of the electric field on either side of the plane of charge. But this doesn't make sense to me already, because this is in conflict with 520,000N/C as the value of the electric field.
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