The Distribution of the Magnetic Field and Return Current Round a Submarine Cable Carrying Alternating Current. Part 2

The following theory of the distribution of magnetic field above a submarine cable carrying alternating currents was developed at the suggestion of the Admiralty, and the experimental verification of the theory by means of a model was carried out at the Admiralty Research Laboratory, Teddington. The results are published by permission of the Admiralty. I have also been allowed to make use of the results obtained by Dr. C. V. Drysdale in a research carried out on the Gareloch in order to compare the theory with measurements made on the sea. In 1897 Mr. C. S. Whitehead published a theory giving the effect of a plane conducting sheet on the field due to a circular current. His results, however, are not in accord with experiment, and it may be shown that his mathematical analysis is unsound. More recently M. Abraham has determined the distribution of current stream lines in a thin conducting sheet due to various sources of alternating current. His results, however, do not cover the present case.