(21-67) (a) Show that at points along the axis of a dipole (along the same line that contains +Q and

(21-67) (a) Show that at points along the axis of a dipole (along the same line that contains +Q and -Q the electric field has magnitude E=1/4πε_02p/r^3, for r≫l (Fig. 21-45), where r is the distance from a point to the center of the dipole. (b) in what direction does E point?