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Electric Field due to Solid Non-Conducting Cylinder

  1. Feb 7, 2012 #1
    1. The problem statement, all variables and given/known data

    Positive charge is distributed throughout a solid non-conducting cylinder of radius 'b ' and infinite length. The charge density increases with radius according to ρ = [itex]{ρ}_{o}[/itex]([itex]{r}{^2}/{b}{^2}[/itex]), where [itex]{ρ}_{o}[/itex] is a constant (evidently equal to the charge density at the surface of the cylinder).

    Find the electric field intensity, E, as a function of radius, outside the cylinder.

    2. Relevant equations

    E = k[itex]{dq}/{r}^{2}[/itex]

    3. The attempt at a solution

    Not sure where to get started, actually. If we try to find the electric field intensity at a position outside the cylinder wouldn't it be dependent on how far out we're finding the electric field and not dependent on the radius?
    Last edited: Feb 7, 2012
  2. jcsd
  3. Feb 7, 2012 #2


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    Gold Member

    This is a straight forward application of Gauss's Law. See example 1.4 which is similar to your problem.


    See also,

    http://www.chem.ox.ac.uk/teaching/Physics%20for%20CHemists/Electricity/Gauss.html [Broken]

    http://research.physics.illinois.edu/PER/unit4.pdf [Broken]
    Last edited by a moderator: May 5, 2017
  4. Feb 13, 2012 #3
    I got the right answer with your help, Spinnor.

    Thanks for the pointing me in the right direction.
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