An electromagnetic wave of frequency $v=3.0 \mathrm{MHz}$ passes from vacuum into a dielectric medium with relative permittivity ${\mathrm{\epsilon }}_{\mathrm{r}}=4.0$. Then

The average total energy density of the electromagnetic wave is. where rms value of the electric field of the light coming from the sun is $720{\mathrm{Nc}}^{-1}$.

Velocity of an electromagnetic waves in a medium depends upon _____.

According to Maxwell's hypothesis, a changing electric field change in

Maxwell in his famous equation of electromagnetism introduced the concept