Calculating Electric field and total charge

[ee1215]

Homework Statement

Surface charge density on gold plate of radium 15cm is 5x10^-9 C/m^2
A) Calculate electric field intensity (E) near plate center
B) Assuming surface charge density is constant over the entire surface of the plate, calculate the total charge on the plate

Homework Equations

En=$\rho$ / $\epsilon$

The Attempt at a Solution

A) En=5x10^-9 C/m^2 / 8.85x10^-12 = 565 V/m
B) Not sure on the total charge equation.

 

[quietrain]

i think it should be E = surface charge density / e₀
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/elesht.html


with regards to total charge, for constant charge density throughout, q= (charge density) x area of plate