Intrinsic Wave Impedance for Conductive Medium

[tquiva]

Homework Statement

I know that for air, the intrinsic impedance η is 377 Ω, but it becomes complex in a conductive medium. This fact is sort of hindering me in being able to answer a few problems consisting of electric and magnetic waves in a conductive medium, but I just wanted to clarify one thing.
Say, I am given H(z,t)=0.5cos(ωt-βz)ay+0.7cos(ωt-βz)ax

Homework Equations

I know that the intrinsic impedance for a conductive medium is:

The Attempt at a Solution

When σ=0 for one problem, I was left with:

But I do know that

My question is, what in the world is u_o, ε_o, and ε_r ?
Am I supposed to figure this out or is this already provided in a table somewhere?
I have been trying to look in my book and online, but am getting confused easily.
Will someone please clarify this for me?
Any help is greatly appreciated!

 

[rude man]

Those are all real constants. mu_0 and epsilon_0 are permeability and permittivity of free space, look them up anywhere, and epsilon_r is the relative permittivity of your medium (= epsilon/epsilon_0).

How you got as far as you did, which is pretty far, without knowing that is a bit of a mysrtery to me, and please believe that I'm nort trying to be condescending or insulting - just wondering!