A cylindrical shell made of insulating material has inner and outer radii of a = 2.0 cm and b = 5.0 cm, respectively, and its volume charge density is given by = +6.0 C/m3. This shell wraps tightly around a cylindrical core made of insulating material (i.e., no air gap between the core and the shell) whose volume charge density is twice as large as that of the shell. Determine the electric field E(r) at a distance of r = 4.0 cm radially outward from the central axis of the core. For the limits check, investigate what happens to the electric field E(r) as r a.