The maximum electron density of the ionosphere layer in the morning is $10^{10} \ m^{-3}$. At noon,the maximum electron density increases to $2 \times 10^{10} \ m^{-3}$. What is the ratio of the critical frequency at noon to the critical frequency in the morning?

Energy stored in electromagnetic oscillations is in the form of

The magnetic field in a plane electromagnetic wave is given by $B = 3.01 \times 10^{-7} \sin(6.28 \times 10^2 x + 2.2 \times 10^{10} t) \, T$,where $x$ is in $cm$ and $t$ is in seconds. The wavelength of the given wave is ....... $cm$.

$A$ mathematical representation of an electromagnetic wave is given by the two equations $E = E_{max} \cos(kx - \omega t)$ and $B = B_{max} \cos(kx - \omega t)$,where $E_{max}$ is the amplitude of the electric field and $B_{max}$ is the amplitude of the magnetic field. What is the intensity $I$ in terms of $E_{max}$ and universal constants $\mu_0, \epsilon_0$?

Consider an electromagnetic wave propagating in a vacuum. Choose the correct statement.

The amplitude of the electric field associated with a light beam of intensity $\frac{15}{\pi} \text{ W m}^{-2}$ is (in $\text{ N C}^{-1}$)