The electric field boundary conditions at the interface between two material media are:
<math> \hat{\mathbf{n}} . \quad [ \mathbf{D_2(r)} - \mathbf{D_1(r)} ] = \rho_s (\mathbf{r}) </math>
The magnetic field boundary conditions at the interface between two material media are:
<math> \hat{\mathbf{n}} \dot . [ \mathbf{B_2(r)} - \mathbf{B_1(r)} ] = 0 </math>