The electric and magnetic fields at an arbitrary point inside matter fluctuate rapidly both in space and time. It is therefore necessary, in the chapter’s introduction, tomake the important distinction between microscopic and macroscopic fields. It is assumed throughout that the electric dipole approximation is valid, and several important properties which apply to matter in bulk are described early on. Along the way, it is convenient to define two new fields D and H, and these appear in a number of questions. Another feature which emerges during this treatment includes the concept of bound charge and current densities, and how these quantities are incorporated intoMaxwell’s inhomogeneous equations. Although Chapter 9 deals exclusively with static fields, it forms an important backdrop to Chapter 10 where some general timedependent aspects of macroscopic electromagnetism are considered.
