On electromagnetic boundary conditions and constitution of homogeneous materials

Modern macroscopic electromagnetism employs four differential equations containing four vector fields, a source charge density, and a source current density. Two of the four fields (i.e., Ẽ (x, t) and B̃ (x, t)) are primitive fields, while the remaining two (i.e., D̃ (x, t) and H̃ (x, t)) are induction fields. Unlike the primitive fields, the induction fields do not have microscopic existence and are not considered fundamental but undoubtedly offer a great deal of convenience [1, 2].