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:

$A$ plane electromagnetic wave of frequency $500\, MHz$ is travelling in vacuum along $y$-direction. At a particular point in space and time,$\overrightarrow{B} = 8.0 \times 10^{-8} \hat{z}\, T$. The value of electric field at this point is (speed of light $c = 3 \times 10^{8}\, m/s$). $\hat{x}, \hat{y}, \hat{z}$ are unit vectors along $x, y$ and $z$ directions.

An electromagnetic wave in vacuum has the electric and magnetic field $\vec{E}$ and $\vec{B}$,which are always perpendicular to each other. The direction of polarization is given by $\vec{X}$ and that of wave propagation by $\vec{k}$. Then:

An electromagnetic wave of frequency $1 \times 10^{14} \,Hz$ is propagating along the $z$-axis. The amplitude of the electric field is $4 \,Vm^{-1}$. What is the energy density of the electric field? (Permittivity of free space $\varepsilon_0 = 8.8 \times 10^{-12} \,C^2 \,N^{-1} \,m^{-2}$)

$A$ plane electromagnetic wave of frequency $35 \ MHz$ travels in free space along the $X$-direction. At a particular point (in space and time) $\overrightarrow{E} = 9.6 \ \hat{j} \ V/m$. The value of the magnetic field at this point is:

The electric field intensity of an electromagnetic wave is ....... to the distance it has traveled.