An infinitely long insulating cylinder of radius R has a volume charge density that varies with the radius as given by the following expression where rho0, a, and b are positive constants and r is the distance from the axis of the cylinder. rho = rho0 a − r b Use Gauss's law to determine the magnitude of the electric field at the following radial distances. (Use the following as necessary: ε0, rho0, a, b, r, and R.)