# Electric field strength

ntk

## Homework Statement

Two plates each have an area of 80cm2 and are placed facing one another in a vacuum. If the top plate carries a positive charge of 25nC and the bottom plate carrie, a charge of -25nC. Find the electric field strength between them.
Permitivity of free space = 8.9 * 10^-12

## Homework Equations

Electrical field strength = surface charge density/permitivity of free space

## The Attempt at a Solution

Should I take the difference of the charge between two plates, which is 50nC, and divide it by the surface area to find the charge density or just use the charge of one plate which is 25nC ?
Thank you.

$$E = \frac{\sigma}{2\epsilon_0}$$