Comparison of the practical advantages of alternative descriptions of electromagnetic momentum

Maxwell´s description of electromagnetism in terms of the ´electrokinetic momentum´ of the ´electrical fluid´, in place of the Faraday concept of magnetic flux, forms a part of an electromagnetic theory which is formulated in terms of charges and potentials, instead of fields. It defines momentum as a property of all moving charge, equally important in DC and power-frequency applications as it is to the communication engineer. It is intimately associated with electromagnetic energy transfer, and to Poynting´s theorem. The author´s purpose is to separate and clarify the various different definitions of electromagnetic momentum which emerge from Maxwell´s suggestion, and to examine their practical advantages, to the engineer, when compared with the usual D*B vector. The planewave is used to illustrate the comparison, together with another example, showing how the obscurities and apparent anomalies which are associated with the momentum concept can be resolved by the change in viewpoint. The relationships with energy flow, on the one hand, and stress, on the other, are briefly examined.<>