Relativity and Parallel Wires
David L. Webster · American Journal of Physics · 1961
Special relativity gives simple answers to the freshmen's persistent questions, “Why should like currents attract, when like charges repel?,” and, “Why should the speed of light come into the laws of parallel-wire forces?” These answers are derived here in two ways: first, to prove them logically sound, from the Lorentz transformations, with v the drift velocity of the carriers; then by essentially equivalent calculations that have been found intelligible and interesting to freshmen.