Note 41 — Chapter XII · THE EQUATIONS OF ELECTROMAGNETICS AND LORENTZ’S THEORY
Reading edition
If two magnetic poles of equal strength, situated in empty space at a distance of one centimetre apart, attract or repel each other with a force of one dyne, either pole is said to represent one unit of magnetic pole strength in the electromagnetic system of units. Owing to the interconnections between magnetism and electricity, we can deduce therefrom the unit of electric charge also in the electromagnetic system. Likewise, if two electric charges of equal strength, also situated in empty space at a distance of one centimetre apart, attract or repel each other with a force of one dyne, either charge is said to represent one unit of electric charge in the electrostatic system of units. From this we may derive the unit of magnetic pole strength in the electrostatic system.