The velocity of radio waves in free space is $3 \times 10^{8} \ m/s$. If the wavelength of the radio waves is $150 \ m$,what is their frequency?

$A$ plane electromagnetic wave is incident on a plane surface of area $A$ normally,and is perfectly reflected. If energy $E$ strikes the surface in time $t$,then the average pressure exerted on the surface is ($c=$ speed of light).

The electromagnetic waves travel in a medium at a speed of $2.0 \times 10^{8} \ m/s$. The relative permeability of the medium is $1.0$. The relative permittivity of the medium will be (in $.25$)

The intensity of the light from a bulb incident on a surface is $0.22 \, W/m^2$. The amplitude of the magnetic field in this light wave is . . . . . . $\times 10^{-9} \, T$. (Given: Permittivity of vacuum $\epsilon_0 = 8.85 \times 10^{-12} \, C^2 N^{-1} m^{-2}$,speed of light in vacuum $c = 3 \times 10^8 \, m/s$)

$A$ point source of $100\,W$ emits light with $5\%$ efficiency. At a distance of $5\,m$ from the source,the intensity produced by the electric field component is:

What is the value of the speed of light in free space?