$A$ sky wave with a frequency of $55 \text{ MHz}$ is incident on the $D$-region of the ionosphere at an angle of $45^\circ$. What is the angle of refraction? (The electron density in the $D$-region is $400 \text{ electrons/cm}^3$).

$A$ plane electromagnetic wave in a non-magnetic dielectric medium is given by $\vec{E} = \vec{E}_0 \sin(4 \times 10^7 x - 50t)$,where distance is in meters and time is in seconds. The dielectric constant of the medium is:

The property which is not of an electromagnetic wave travelling in free space is that:

An electromagnetic wave has an electric field given by the expression (in Cartesian coordinates) $\vec E(x,t) = 6.0\,\cos(1 \times 10^7x - 3 \times 10^{15}t)\hat z$. What is the direction of the magnetic field at time $t = 0$ and position $x = 0$?

The ratio of the amplitude of the magnetic field to the amplitude of the electric field for an electromagnetic wave propagating in vacuum is equal to:

The quantities $x = \frac{1}{\sqrt{\mu_{0} \varepsilon_{0}}}$,$y = \frac{E}{B}$,and $z = \frac{l}{CR}$ are defined,where $C$ is capacitance,$R$ is resistance,$l$ is length,$E$ is electric field,$B$ is magnetic field,and $\varepsilon_{0}, \mu_{0}$ are free space permittivity and permeability respectively. Then: