The average value of electric energy density in an electromagnetic wave is:

$A$ plane electromagnetic wave travels in a medium of relative permeability $\mu_{r} = 1.61$ and relative permittivity $\epsilon_{r} = 6.44$. If the magnitude of the magnetic intensity $H$ is $4.5 \times 10^{-2} \; A m^{-1}$ at a point,what will be the approximate magnitude of the electric field intensity $E$ at that point? (Given: $\mu_{0} = 4 \pi \times 10^{-7} \; N A^{-2}$,$c = 3 \times 10^{8} \; m s^{-1}$)

Suppose that the electric field of an electromagnetic wave in vacuum is $E = (3.1 \text{ NC}^{-1}) \cos [(1.8 \text{ rad m}^{-1}) y + (5.4 \times 10^6 \text{ rad s}^{-1}) t] \hat{i}$. What is the wavelength $\lambda$ (in $\text{ m}$)?

Which of the following pairs of components can produce a plane electromagnetic wave propagating in a direction such that the electric field $\vec{E} = (E_x\hat{i} + E_y\hat{j} + E_z\hat{k})$ and magnetic field $\vec{B} = (B_x\hat{i} + B_y\hat{j} + B_z\hat{k})$ vary with position and time?

The electric field part of an electromagnetic wave in vacuum is
$E = 3.1 \, N C^{-1} \cos [ (1.8 \, rad \, m^{-1}) y + (5.4 \times 10^8 \, rad \, s^{-1}) t ] \hat{i}$
The wavelength of this part of the electromagnetic wave is ...... $m$.

An electromagnetic wave travelling in a lossless dielectric medium having a dielectric constant $\epsilon_r = 9$, has the electric field, $E_x = E_0 \sin (kz - 2\pi \times 10^6 t) \text{ Vm}^{-1}$ where $E_0$ is the amplitude and $k$ is the wave vector. Among the following options, the incorrect choice is :