For a transparent medium relative permeablity and permittlivity, $\mu_{\mathrm{r}}$ and $\epsilon_{\mathrm{r}}$ are $1.0$ and $1.44$ respectively. The velocity of light in this medium would be,

The vector $\vec E$ and $\vec B$ of an electromagnetic wave in vacuum are

If a source of power $4\ kW$ produces $10^{20}$ photons/second , the radiation belongs to a part of the spectrum called

In an electromagnetic wave the energy density associated with magnetic field will be

Light with an energy flux of $25 \times {10^4}$ $W/m^2$  falls on a perfectly reflecting surface at normal incidence. If the surface area is  $15\,\, cm^2$ the average force exerted on the surface is