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Electric Field Problem stuck

  1. Jul 9, 2008 #1
    Yet another problem I'm stuck on tonight...

    The membrane surrounding a living cell consists of an inner and an outer wall that are separated by a small space. Assume that the membrane acts like a parallel plate capacitor in which the effective charge density on the inner and outer walls has a magnitude of 7.1x10^-6 C/m^2. (a) What is the magnitude of the electric field within the cell membrane? (b) Find the magnitude of the electric force that would be exerted on a potassium ion (K+; charge = +e) placed inside the membrane.

    No clue... lol.
  2. jcsd
  3. Jul 10, 2008 #2


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    Is it possible to model the membrane as a spherical shell? That seems to be the only way since the shape of the membrane isn't described. Just use Gauss law here.
  4. Jul 10, 2008 #3


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    They want you to treat the membrane as a parallel plate capacitor. To start, what is the relationship between the charge density on the plate of a parallel plate capacitor and it's electric field?
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