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:
“She went in there to muse on being rid
Of relative beneath the coffin lid.
No one was by. She stuck her tongue out; slid.”
—Gwendolyn Brooks (b. 1917)
“To fight aloud is very brave,
But gallanter I know,
Who charge within the bosom
The Cavalry of Woe.”
—Emily Dickinson (1830–1886)