An electromagnetic wave travels in a medium with a speed of $2 \times 10^8 \ m/s$. The relative permeability of the medium is $1$. Then the relative permittivity is:

The electric field component of a monochromatic radiation is given by
$\vec E = 2E_0 \hat i \cos kz \cos \omega t$
Its magnetic field $\vec B$ is then given by

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 $c = 3 \times 10^{8} \; m/s$)

The frequency of an electromagnetic wave is $25 \ MHz$. If the magnitude of the electric field at a point at any instant is $6.3 \ V/m$,then the magnitude of the magnetic field at that point is ..... $Wb/m^2$.

The velocity of electromagnetic radiation in a medium of permittivity $\varepsilon_{0}$ and permeability $\mu_{0}$ is given by

The layer of the atmosphere that reflects low frequency $(LF)$ electromagnetic waves during day time only is