Interface conditions for electromagnetic fields
= Interface conditions for electromagnetic fields
{wiki}
Across an interface with unit normal $\mathbf n$ from medium one to medium two, <Maxwell equations> imply $\mathbf n\times(\mathbf E_2-\mathbf E_1)=0$, $\mathbf n\cdot(\mathbf B_2-\mathbf B_1)=0$, $\mathbf n\cdot(\mathbf D_2-\mathbf D_1)=\sigma_f$, and $\mathbf n\times(\mathbf H_2-\mathbf H_1)=\mathbf K_f$. Here $\sigma_f$ and $\mathbf K_f$ are the free surface <electric charge> and <electric current> densities.