Gauss's Law: Charge Distribution in Cylinder Volume

[Toyona10]

Homework Statement

Charge is distributed uniformly throughout the volume of an infinitely long cylinder of radius R.
a)Show that at a distance r from the cylinder (r<R): E= (ρ*r)/2ε° where ρ is the volume charge density and (b) write and for E when r>R

Homework Equations

The Attempt at a Solution

hey guys...i was able to prove the first part:
as q= ρv= ρ∏r^2 * L

EA= Q/ε

E= (ρ∏r^2L)/ε°2∏rL >> after cancelling i got that expression in the question...

and about the b part, do we just do the same thing...which r do we substitute? Please help asap

 

[rude man]

It's the same old Gauss law! EA = q/e0 as you say.
What are q and A now?