Electric Absorption (85) When the dielectric of which the condenser is formed is not a perfect insulator the phenomena of conduction are combined with those of electric displacement. The condenser, <s>after being<\s> when left charged gradually loses its charge and in some cases after being discharged completely it gradually acquires a new charge of the same sign as the original charge, and this finally disappears These phenomena have been described by Faraday (Series XI and by M,sup>r<\sup>r F Jenkin (Report to Board of Trade on Submarine Cables) and may be classed under the name of "Electric Absorption" (86) We shall tke the case of a condenser of any number of parallel layers of different materials. If a constant difference of potentials <s>is kept up<\s> between its extreme surfaces is kept up for a sufficient time till a condition of permanent steady flow of electricity is established, then each bounding surface will have a charge if electricity depending on the nature of the substance on each side of it. If the extreme surfaces be now discharged, these internal charges will gradually be dissipated and a certain charge may reappear on the extreme surfaces if they are insulated, or, if they are connected by a conductor a certain quantity of electricity may be urged through the conductor during the reestablishment of equilibrium Let the thickness of the several layers of the condenser be a<sub>1<\sub> a<sub>2<\sub> &c <s>and the whole thickness a<\s> Let the values of k for these layers be respectively k<sub>1<\sub> k<sub>2<\sub> k<sub>3<\sub> and let <s>a<sub>1<\sub>/k<sub>1<\sub> + a<sub>2<\sub>/k<sub>2<\sub> &c = a/k<\s> a<sub>1<\sub>k<sub>1<\sub> + a<sub>2<\sub>k<sub>2<\sub> &c = ak (50) where k is the "electric elasticity" of air and a is the thickness of an equivalent condenser of air
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Manuscript details
 Author
 James Clerk Maxwell
 Reference
 PT/72/7
 Series
 PT
 Date
 1864
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Cite as
J. C. Maxwell’s, ‘Dynamical theory of the electromagnetic field’, 1864. From The Royal Society, PT/72/7
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