Definitions and roles of the electromagnetic field vectors

Contrasting views on electromagnetic fundamentals, usually associated with physicists and engineers, are summarised in the roles allocated to the field vectors. Whereas most engineers view the electrical and magnetic flux densities D and B as analogous quantities, while E and H both denote field strength, to the physicist the vectors E and B are sufficient measures of the field, in vacuo, and D and H are paired as auxiliary quantities. The underlying differences of understanding have led to a plea by physicists for greater agreement. The paper shows that the use of the retarded potentials as the primary measures of the field gives a clear and unambigous definition of each of the field vectors, and shows the need for eight, not four. This helps to clarify the conceptual difficulties underlying much debate. It suggests that simplicity of understanding requires the adoption of the physicist´s view, but that this need not imply any major changes in the ways in which the field vectors are used by engineers