The easiest way to Heaviside ellipsoid

The formula for the electric field of a point charge moving with constant velocity is derived using the symmetry properties of Maxwell's equations - its Lorentz invariance. In contrast to conventional treatments, the derivation presented does not use retarded integrals or relativity transformations.Comment: 5 page

On vector potential of the Coulomb gauge

The question of an instantaneous action (A M Stewart 2003 Eur. J. Phys. 24, 519) can be approached in a systematic way applying the Helmhotz vector decomposition theorem to a two-parameter Lorenz-like gauge. We thus show that only the scalar potential may act instantaneously.Comment: REVTEX4, 7 page