Solution (source code)

= Solution

Substitute the monochromatic <plane waves> into the two divergence equations of <Maxwell's equations>. They become $ik E_{0z}=0$ and $ik B_{0z}=0$. For nonzero wavenumber,
$$
\boxed{E_{0z}=B_{0z}=0.}
$$
Thus both fields are transverse to the direction of propagation. The wave equation also gives the vacuum <dispersion relation> $\omega^2=c^2k^2$.