# Electric Field Problem stuck

1. Jul 9, 2008

### WGDawg3

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. Jul 10, 2008

### Defennder

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.

3. Jul 10, 2008

### alphysicist

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?