Dimensions of Electrical and Magnetic Quantities

Abstract

FOR rather more than ten years the rationalized M.K.S. system of units has been generally accepted as the most satisfactory one to employ for practical calculations involving electrical and magnetic quantities^1,2. This system side-steps the question of dimensions by introducing two unfortunate expressions—permittivity and permeability of free space—and assigning to them, respectively, the values 10⁻⁹/36π farad/metre and 4π × 10⁻⁷ henry/metre. Any dislike aroused by these terms may, however, be easily overcome by giving them new names: electric factor and magnetic factor, the question of units being left until later.