Electomagnetic waves, radiation

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• Phase velocity of an electromagnetic wave:$$v= \frac{c}{\sqrt{\varepsilon \mu}},$$ where $$c= \frac{1}{\sqrt{\varepsilon_0 \mu_0}}$$
• In a travelling electromagnetic wave:$$E\sqrt{\varepsilon \varepsilon_0} = H\sqrt{\mu \mu_0}.$$  
• Space density of the energy of an electromagnetic field:$$ \omega = \frac{\vec{E}.\vec{D}}{2}+\frac{\vec{B}.\vec{H}}{2}.$$
• Flow density of electromagnetic energy, the Poynting vector:$$\vec{S}=\vec{E}\times\vec{H}.$$
• Energy flow density of electric dipole radiation in a far field zone:$$S \sim \frac{1}{r^2} \sin^2 \theta,$$where $r$ is the distance from the dipole, $\theta$ is the angle between the radius vector $\vec{r}$ and the axis of the dipole.
• Radiation power of an electric dipole with moment $\vec{p}(t)$ and of a charge $q$, moving with acceleration $\vec{w}$: $$P = \frac{1}{4\pi\varepsilon_0}\frac{2\ddot{\vec{p}}^2}{3c^3}, P = \frac{1}{4\pi\varepsilon_0}\frac{2q^2 w^2}{3c^3}.$$