Electric Field in a living cell

[arod2812]

Homework Statement

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 5.77 x 10-6 C/m2. (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.

Homework Equations

I don't understand what the second part of this question entails. What does +e tell me?

The Attempt at a Solution

I think i understand that the first part is E=5.77E-6/8.8542E-12 because E=sigma/E(not)
Therefore, I replace the charge density (sigma) with the charge density for an electron??

 

[blochwave]

The positively charged potassium ion is missing an electron, so its charge +1.602x10^-19 coulombs, that's what +e means

I believe you did part a) right, as long as your equations and numbers are right

Regardless, it's similar to the other problem you posted. You have found the electric field in part A, and now you want to know the force exerted on a charge +e by that electric field. Same equation you used in the other problem