2.1.1 E, D, H, B

The description of an electromagnetic (EM) field in any material, including vacuum, requires four basic vectors. Everybody uses the following notation and we call them E, D, H, B; everybody, of course, agrees about their physical interpretation, however there are some disagreements about their names. E is always designated as the electric field. When introduced for the first time by Maxwell, D had been called the "electric displacement vector," some people now prefer the expression "electric induction vector." The same ambiguity is found for B and H which are often, respectively, called the "magnetic induction vector" and the "magnetic field vector." In a more recent trend B is the "magnetic vector" and H the "magnetic excitation vector." The author has no clear-cut opinion, but he considers that E and D are attached to electric properties, while H and B correspond to magnetic properties.

Since optical materials, by definition, are transparent, they don't usually have any magnetic properties; so H and B are strictly proportional and are thus collinear, the proportionality coefficient is called the vacuum permeability ? ₀ = 4 ? 10 ^?7 (SI units, henry/meter (H/m)), B = ? ₀ H.

For electric vectors, the situation is more complicated. Except in the very special case of nonlinear optics, the relationship between E and D is linear. For isotropic...