The same volume-averaging procedure used in Chapter 2 shows how to transition from the Maxwell’s equations controlling the electromagnetic fields of fundamental particles in vacuum to the continuum form of Maxwell’s equations describing the electromagnetic fields averaged over large numbers of molecules. The Maxwell stress tensor is derived for the body forces acting on the molecules. The macroscopic form of Maxwell’s equations and the associated electromagnetic fields are obtained when the frame of reference is moving with the center of mass of each collection of molecules. The laws of reversible polarization are obtained by time differentiation of the electromagnetic energy density. The law of electromigration (Ohm’s law) is obtained from a nonequilibrium thermodynamics perspective. Conditions are obtained for the neglect of the material movement in the continuum theory of electromagnetism. Electromagnetic continuity conditions are derived and used on example problems. The continuum form of Newtonian gravity is derived. Expressions for the Coriolis and centrifugal forces are derived when the frame of reference is rotating about an axis.