An electromagnetic wave has a frequency of $3 \text{ MHz}$ in free space. When this wave passes through a medium with a relative permittivity $\varepsilon_r = 4.0$,its frequency will be:

For which of the following media will the wave propagation occur without experiencing attenuation?

What is the value of the speed of light in free space?

The electromagnetic waves travel with a velocity

The refractive index of the ionosphere is

The electric field in an electromagnetic wave is given by $E = 56.5 \sin \omega(t - x/c) \; NC^{-1}$. Find the intensity of the wave if it is propagating along the $x$-axis in free space. (Given $\varepsilon_{0} = 8.85 \times 10^{-12} \; C^{2} N^{-1} m^{-2}$ and $c = 3 \times 10^{8} \; m/s$)