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Homework Help: Find net electric field in a wire?

  1. Sep 10, 2015 #1
    After solving this problem I ended up with--(2a is the length of the wire)(integral limit is from -a to +a)
    (x is the ⊥ distance from centre of the wire to a point P where we have to find the net field )
    E[SUBx]= (1/4Πε)*(Q/2a)∫x.dy/(x^2+y^2)^3/2

    P.S- sorry, I'm not able to upload the image of the problem. This is my first time ever at this site.
    Help me in solving this integral.
    Detailed solution would be appreciated . ☺
  2. jcsd
  3. Sep 10, 2015 #2


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  4. Sep 13, 2015 #3


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    Homework Helper

    Do you want the electric field in the wire or around the wire at some point in space ##P##? I'm assuming you want the electric field at some point ##P##.

    The easiest way to do this problem is to position the wire along the z-axis and enclose it in a cylindrical Gaussian surface. Then using Gauss' law, find the magnitude of the electric flux density ##| \vec D |## in terms of the enclosed charge.

    Then using ##\vec D = \varepsilon \vec E##, you will be able to find the electric field.

    Hint: The electric flux density ##\vec D## points radially outwards from the cylinder, so in cylindrical co-ordinates we can write it as ##\vec D = |\vec D| \hat r##.
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