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Homework Help: Potential difference and current

  1. Feb 12, 2007 #1
    1. The problem statement, all variables and given/known data

    A typical cell membrane is 8.0 nm thick and has an electrical resistivity of 1.3 10^7 m. If the potential difference between the inner and outer surfaces of a cell membrane is 75 mV, how much current flows through a square area of membrane 1.3 ┬Ám on a side?

    2. Relevant equations

    I was thinking to use R=p(L/A) and then V=IR to solve for the current, but I wasn't sure what to use for numbers. I know that V=75 mV and p=1.3 x 10^7, but would L=1.3 micrometers and A=L x 8.0 nm ?
  2. jcsd
  3. Feb 12, 2007 #2


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    Gold Member

    First find the resistance, R, by using the formula you wrote down: R=p(L/A). You know the length, L, which is like the thickness. The area, A, is also given and you know the resistivity of the specimen. Whats the problem?
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