For an infinite surface with uniform charge density ,

the electric field immediately above and below the surface has a discontinuity

which isE+E=0n^

Justify the discontinuity with the following instructions:

According to Newton's 3rd law, for every action, there is an equal and opposite reaction, the infinitesimal surface charge element cannot exert any force on itself, but the force must come from electric field induced by all charge in space excluding this surface charge element.

Consider the electric field around an infinitely large charged surface.

Think about which part of the charge distribution is responsible for the discontinuity.