# Transformation of epsilon and miu

1. Jul 5, 2007

### bernhard.rothenstein

consider Coulomb's law in medium. You find there epsilon. Consider the expression for the magnetic field generated by an electric current in the same medium (nonconducting, homogeneous and isotropic). Please let me know how do they transform when we consider them from two inertial reference frames in relative motion.
Thanks

2. Jul 5, 2007

### Meir Achuz

The equation D=epsilon E is only valid in the rest system of a medium.
This system is a preferred system. Do all calculations in this system.
Then you can Lorentz transform any relativistic tensor quantity.
epsilon, mu, B, D do not transform as tensors, even though some texts imply that they do.