From this equation, we see that the normal component of the electric field indeed undergoes a jump through the charged interface. This is equivalent to a jump relation of the potential theory. As a second step, the two expressions for E m ± ± are substituted into the interfacial boundary condition σ σ − − E m − − ⋅ ⋅ n m = σ σ + E m + ⋅ ⋅ n m , applied to every facet 𝑚. This operation leads to a system of linear equations for unknown charge densities ρ ρ m which solves the problem: