To radiate $EM$ signal of wavelength $\lambda$ with high efficiency,the antennas should have a minimum size equal to

$A$ plane electromagnetic wave of frequency $25 \text{ MHz}$ travels in free space along the $X$-direction. At a particular point in space and time,the magnetic field is $\overrightarrow{B} = 2.1 \times 10^{-8} \hat{k} \text{ T}$. Find the electric field $\overrightarrow{E}$ at this point.

How is the average energy density in an electromagnetic wave related to the magnetic field?

$A$ sky wave with a frequency $55 \, MHz$ is incident on the $D$-region of the Earth's atmosphere at $45^\circ$. The angle of refraction is ......... $^\circ$ (electron density for the $D$-region is $400 \, \text{electrons}/cm^3$).

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:

In the case of electromagnetic waves,which of the following statements is incorrect?