When $EM$ wave propagates through vacuum then

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

A $1.5 \,kW$ laser beam of wavelength $6400 \,\mathring A$ is used to levitate a thin aluminium disc of same area as the cross-section of the beam. The laser light is reflected by the aluminium disc without any absorption. The mass of the foil is close to ……… $kg$

The electric field in an electromagnetic wave is given as $\vec{E}=20 \sin \omega\left(t-\frac{x}{c}\right) \vec{j} NC ^{-1}$ Where $\omega$ and $c$ are angular frequency and velocity of electromagnetic wave respectively. The energy contained in a volume of $5 \times 10^{-4}\, m ^3$ will be $…..\times 10^{-13}\,J$

(Given $\varepsilon_0=8.85 \times 10^{-12}\,C ^2 / Nm ^2$ )

A plane electromagnetic wave travels in a medium of relative permeability $1.61$ and relative permittivity $6.44$. If magnitude of magnetic intensity is $4.5 \times 10^{-2} \;Am ^{-1}$ at a point, what will be the approximate magnitude of electric field intensity at that point$?$

(Given : permeability of free space $\mu_{0}=4 \pi \times 10^{-7}\;NA ^{-2}$, speed of light in vacuum $c =3 \times 10^{8} \;ms ^{-1}$ )