Capacities

Considering that electrostatic energy is actually in the space surrounding a charged body, the latter is called a "terminal surface." It is shown that capacity is predominantly a function of the maximum lineal dimension of the terminal surface. The volumetric and lineal energy densities in the field are defined and studied in a number of cases. It is proven that the capacity between two terminal surfaces is greatly affected by changing the lineal dimensions of the smaller terminal surface, but not so for changes of the larger. Certain current errors in connection with "mutual capacity" are considered. The practical applications to a radio antenna and to aeroplane counterpoises are given. When a charge traverses a sphere, entering parallel to a diameter, the sphere behaves as a conductor of uniform lineal capacity. Applications of the theoretical considerations are also given in connection with the conductivity of concentrated and dilute electrolytes.