Calculating Surface Charge Density

[angryshoe]

Homework Statement

The electric field strength just above one face of a copper penny is 2310 N/C.

What is the surface charge density on this face of the penny?

Homework Equations

Surface Charge Density = Q/A

The Attempt at a Solution

The only thing that I can understand is that surface charge density is equal to Q/A but that does not seem to help me with this question. What can I do for this problem?

Edit: I figured out how to do this problem.

 

[granpa]

I think [/color]you are meant to assume that the surface charge density is constant. you do know how to calculate the field of an infinite plane of constant surface charge density, right?