I can't figure out how to find the charge density for the following problem:
A conductor is placed in an external electrostatic field. The external field is uniform before the conductor is placed within it. The conductor is completely isolated from any source of current or charge.
Assume that at some point just outside the surface of the conductor, the electric field has magnitude E and is directed toward the surface of the conductor. What is the charge density n on the surface of the conductor at that point?
I'm supposed to express my answer in terms of $E$ and $\epsilon_0$.
I know that Electric Flux = Normal Angle x Electric Field x cos(theta), but I don't know how to relate this to charge density?
What am I missing to solve this problem? This is very basic, I know, but I'm stumped. The hints on Mastering Physics also aren't really helping.