$A$ plane electromagnetic wave is given by $E_z = 100 \cos(6 \times 10^8 t + 4x) \text{ V/m}$. The refractive index of the medium in which the wave is traveling is:

$A$ point source of electromagnetic radiation has an average power output of $800\,W$. The maximum value of the electric field at a distance of $4.0\,m$ from the source is...$V/m$

An electromagnetic wave of frequency $\nu = 3.0\,MHz$ passes from vacuum into a dielectric medium with permittivity $\varepsilon = 4.0\varepsilon_0$. Then

$A$ plane electromagnetic wave of wavelength $\lambda$ has an intensity $I$. It is propagating along the positive $Y$-direction. The allowed expressions for the electric and magnetic fields are given by:

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:

The radiation energy emitted per second by a point source is $100 \,W$. If the efficiency of the source is $4 \%$, then the rms value of the electric field at a distance of $2 \,m$ is [use $\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9$ in $SI$ units].