A plane electromagnetic wave of frequency $$20 \mathrm{~MHz}$$ travels through a space along $$x$$-direction. If the electric field vector at a certain point in space is $$6 \mathrm{~Vm}^{-1}$$, then what is the magnetic field vector at that point?

What feature of the infrared waves make it useful for the haze photography?

Speed of electromagnetic wave in a medium having relative permittivity $$\varepsilon_r$$ and relative permeability $$\mu_r$$ is (speed of light in air, $$c=3\times10^8$$ m/s)

A 30 mW laser beam has a cross-sectional area of 15 mm². The magnitude of the maximum electric field in this electromagnetic wave is given by

[Permuittivity of space, $$\varepsilon_0=9\times10^{-12}$$

Speed of light, $$c=3\times10^8$$ m/s]