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Homework Help: Gauss's Law: I need to check this answer

  1. Sep 20, 2005 #1
    A conducting sphere of radius [tex]10 \mbox{ cm}[/tex] has an unknown charge. If the electric field [tex]17 \mbox{ cm}[/tex] from the center of the sphere has the magnitude [tex]3.2 \times 10 ^3 \mbox{N/C}[/tex] and is directed radially inward, what is the net charge on the sphere?


    [tex]R = 10 \mbox{ cm}[/tex]

    [tex]r = 17 \mbox{ cm}[/tex]

    Gauss's Law:

    [tex]Q _{\mbox{Enc}} = \epsilon _0 \Phi = \epsilon _0 \oint \vec{E} \cdot d\vec{A} = -\epsilon _0 EA = -\epsilon _0 E \left( 4 \pi r^2 \right) \approx -3.6 \times 10^{-9} \mbox{ C}[/tex]

    Is there anything wrong here? I am not sure.

    Any help is highly appreciated.
  2. jcsd
  3. Sep 20, 2005 #2

    Tom Mattson

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    Gold Member

    I don't have a calculator handy so I can't comment on your numerical answer, but all your other steps are fine.
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