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Homework Help: A question on E Flux and Fields

  1. Mar 18, 2017 #1
    1. The problem statement, all variables and given/known data
    1. The field for an infinite charged sheet is found to be σ/2ε0. If we place 2 infinite sheets of opposite charge above one another, we say that the field in between the sheets is σ/ε0 due to the superposition of individual fields.

    Why can't we say the same for a situation where a conducting sphere is embedded in another, and there is charge Q on the outer surface on the inner sphere and -Q on the inner surface of the outer sphere? By same I mean applying superposition on fields by Q and -Q.

    2. Relevant equations

    3. The attempt at a solution
    The only reason i could think of was that it was impossible (to me) to find a Gaussian surface capable of enclosing the charge on the inner surface on the outer sphere, which was hardly a rigorous explanation.

    Any help is much appreciated!
  2. jcsd
  3. Mar 18, 2017 #2


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    The fields in the case of the spheres are also a superposition of the individual fields. It is just that the field inside a spherically symmetric charge shell is zero.
  4. Mar 18, 2017 #3
    Apologies, but I might not have put the question across properly, it was in relation to this problem (part a).

    I tried to solve by finding the field of the inner cylinder using flux, after which I was confused on whether or not i should be doing any "superposition" with the field by the inner surface of the outer cylinder. I then found out that that would've been a mistake, and the field was actually just due to the inner one.

    E = Q/(2πrhε0)

    Thank you for helping!

    Screen Shot 2017-03-18 at 4.43.19 PM.png
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