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

The electric field part of an electromagnetic wave in a medium is represented by:
$E_x = 0;$
$E_y = 2.5 \, \text{N/C} \cos \left[ \left( 2\pi \times 10^6 \, \text{rad/s} \right) t - \left( \pi \times 10^{-2} \, \text{rad/m} \right) x \right];$
$E_z = 0.$
The wave is:

An electromagnetic wave,going through vacuum,is described by $E = E_0 \sin(kx - \omega t)$. Which of the following is independent of wavelength?

In free space,an electromagnetic wave of $3 \; GHz$ frequency strikes an object of size $\frac{\lambda}{100}$,where $\lambda$ is the wavelength of the wave in free space. The phenomenon that occurs is .....

$A$ plane electromagnetic wave is moving in free space with velocity $c = 3 \times 10^8 \ m/s$ and its electric field is given as $\vec{E} = 54 \sin(kz - \omega t) \hat{j} \ V/m$, where $\hat{j}$ is the unit vector along the $y$-axis. The magnetic field vector $\vec{B}$ of the 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: $\mu_{0} = 4 \pi \times 10^{-7} \; N A^{-2}$,$c = 3 \times 10^{8} \; m s^{-1}$)