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Electric field between two wires and gauss law

  1. Jul 5, 2007 #1
    I'm not entirely sure how to word this without a diagram, but please bare with me!

    In an ideal case, the charge on a wire is evenly distributed.
    According to Gauss' Law, an electric field from a charged wire decays with 1/r
    where r is the distance from the centre of the wire.

    Say two wires, with equal and opposite charge and a large radius, R, are placed very close together.
    At the closest points, the electric field will appear as if between parallel plates.
    When close together, the charge distribution will not be even around the circumference of the wire. How would one go about calculating the charge distribution?

    Ultimately looking towards calculating the x component of the electric field in the z direction, ie moving through the gap between the wires.

    Any help on this would be much appreciated, even just to be pointed in the direction of a relevant book or website.

  2. jcsd
  3. Jul 6, 2007 #2


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    Staff: Mentor

    Welcome to the PF, frankness. Do you have a textbook that covers electrostatics? This type of situation is usually covered in the sections that discuss how to calculate capacitance for different geometries (like a parallel-wire transmission line, which is the situation you are asking about).

    To find something online for you, I did a Google Images search on electric field capacitance of parallel wire transmission line, and got some good hits. Here's the hit list:


    And here's a good tutorial from MIT:


    Hope that helps. Feel free to post follow-up questions after you have gone through the materials some.
  4. Jul 7, 2007 #3
    Thanks that MIT link is excellent.
    I only have a basic E&M textbook and have been finding it hard to get to the library outside of my work hours.

    I'll try working through it over the next few days and see how I get on.
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