A long tube charge with charged with uniform spatial density [tex]\rho[/tex]. The inner radius of the tube is: a The outer radius of the tube is: b Need to find the electric field in: a<r<b My approach is Gauss: E*S=4 [tex]\pi[/tex] kq The S is the Gaussean Surface it should be 2 [tex]\pi[/tex] r^2 ?? and q should be [tex]\rho[/tex]*(r^2-a^2)??