Four Macroscopic Vectors of Electromagnetism

Abstract

ASSOCIATED with the change to SI units, there has been considerable discussion of the roles of the vectors H and D in electromagnetism. Much of the confusion arises from the fact that many people do not appreciate how the macroscopic vectors H and D arise when the macroscopic theory of electromagnetism is developed from a microscopic theory. In a microscopic classical theory, for field points in the space between electrons and atomic nuclei, the microscopic electric intensity e and the microscopic magnetic induction b suffice in Maxwell's equations. If the positions and velocities of every atomic charge and atomic magnetic moment are given, then in principle e and b could be calculated. The force on a point charge q would be given by the Lorentz force expression where u is the velocity of the test point charge.