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Homework Help: Linear superposition for electric field

  1. Sep 13, 2015 #1
    1. The problem statement, all variables and given/known data

    A rather large non conducting slab of area A and thickness d has a charge density given by ρ = αx2.
    The origin is through the center of the slab. That is, it bisects the slab into two equal volumes of d/2 thickness and with an area A, with -L/2 to the left of x=0 and L/2 to the right of x=0.

    Suppose there is a large thin plate of UNIFORM charge density sigma on the left side of the aforementioned slab. What is the E field (everywhere) due to this system? Derive an expression for the electric field for the thin plate and then apply the superposition principle. Also give the domains on X for the regions chosen.

    Note: You will not have just one answer.

    3. The attempt at a solution

    I found the E field everywhere due to the slab & due to the thin plate. Now for the E field everywhere, I should break this problem down into four regions and find the superposition of E field in these regions (due to slab and plate):


    -d/2 < x < 0



    Is this correct?
  2. jcsd
  3. Sep 13, 2015 #2


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    2017 Award

    Staff: Mentor

    I would expect that you can combine regions 2 and 3 into a single formula, but splitting them up is not wrong.

    d and L are the same thing?

    Is x2 meant to be x2?
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