It is frequently stated that the electric field of the macroscopic Maxwell equations is the mean of that of the microscopic Maxwell equations. By “mean” is meant either a volume average or a statistical average, the result being the same. In this paper, the electrostatic field is considered, and it is shown that the mean microscopic field is not appropriate for use in the concept of dielectric constant. A suitable definition of macroscopic field is discussed, and it is shown that it differs from the mean microscopic field in a nonuniform medium.

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