1. The problem statement, all variables and given/known data http://i.minus.com/jbxXiQZmmiOQtS.png [Broken] 2. Relevant equations Elecric flux = Integral of closed surface of E dotted into dA = qenclosed / ε0 Rho = 50 x 10^-6 abs(z) 3. The attempt at a solution Integral of closed surface of E dotted into dA will end up being EA when E is constant. as such, EA =qenclosed / ε0 I believe I have to use the function of the Rho in the integral qenclosed = Intergal Rho * dV As given we know to find dV we use the area (A) multiplied by dz. Such as that A * 50 x 10^-6 * Integral abs(z) dz It here I believe that defining the limits tells us rather we are taking from within inside or outside. In my notes we are using a cylinder bar and Gaussian surface of a ring and going from 0 to R (R radius being that of cylinder bar) for inside and 0 to r (r being distance from center of cylinder bar to ring). I have no idea what to put for my limits to get the inside and outside. Moderator note: Moved to the introductory physics forum.