Potential difference and current

map7s

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 µm 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 ?

ranger

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?