Relative Charge Density
From the perspective of the theory of relativity, the length of a segment of wire depends on velocity of observer, so charge density is a relative concept. Anthony French has described how the magnetic field force of a current-bearing wire arises from this relative charge density. He used (p 260) a Minkowski diagram to show "how a neutral current-bearing wire appears to carry a net charge density as observed in a moving frame." The approach to electromagnetism through spacetime symmetry is called relativistic electromagnetism.
Read more about this topic: Charge Density
Famous quotes containing the words relative and/or charge:
“In a country where misery and want were the foundation of the social structure, famine was periodic, death from starvation common, disease pervasive, thievery normal, and graft and corruption taken for granted, the elimination of these conditions in Communist China is so striking that negative aspects of the new rule fade in relative importance.”
—Barbara Tuchman (1912–1989)
“The Germans are called brutal, the Spanish cruel, the Americans superficial, and so on; but we are perfide Albion, the island of hypocrites, the people who have built up an Empire with a Bible in one hand, a pistol in the other, and financial concessions in both pockets. Is the charge true? I think it is.”
—E.M. (Edward Morgan)