Show that the normal component of electrostatic field has a discontinuity from one side of a charged surface to another given by `(E_2 - E_1) hatn= (sigma)/(epsilon_0)` where `hatn` is a unit vector normal to the surface at a point and is the surface charge density at that point. (The direction of`hat n` is from side 1 to side 2.) Hence show that just outside a conductor, the electric field is`sigma hatn // epsilon_0`