A problem arises if we are dealing with a situation in which there are both “electrostatic” and “electromagnetic” quantities. The “mixed system”, which is used very frequently, in CGS literature, uses...A problem arises if we are dealing with a situation in which there are both “electrostatic” and “electromagnetic” quantities. The “mixed system”, which is used very frequently, in CGS literature, uses esu for quantities that are held to be “electrostatic” and emu for quantities that are held to be “electromagnetic”, and it seems to be up to each author to decide which quantities are to be regarded as “electrostatic” and which are “electromagnetic.
