A dipole field , and a quadrupole field , and a total electric charge Q = 0.5. The colour code represents the radial electric field E_r plotted on the NS surface (within the circle that delimits the surface) and in a meridian plane perpendicular to the line of sight (outside the circle that delimits the NS surface). Magnetic field lines with a foot on the surface in the same meridian plane are plotted as well.