An infinite cylindrical rod of radius, r, oriented along the z-axis has both a volume charge density, rho = rho0 s r, that only depends on the radial distance, s, and a surface charge, λ = λ0, so that the entire rod is electrically neutral. note: s, ϕ and z are the coordinates in the cylindrical coordinate system. (a) determine the magnitude and direction of the electric field in all regions of this system. explain all of your assumptions. (b) determine the potential difference between a point along the z-axis and a point on the surface of the rod, i. e. calculate v[s = r] - v[s = 0].