Assuming an EM wave traveling inside an electrically neutral dielectric material. The following electric field describes the EM.
Using the 3rd Maxwell equation, the associated magnetic field is derived as
then, using the 4th Maxwell equation, I got the equality
Does it mean that there is a dependency between the material properties ($\mu$ and $\varepsilon$) and the wave frequency? It seems to be a little bit strange since that $\mu$ and $\varepsilon$ usually are constants.