For a radiation of $9 \text{ GHz}$ passing through air,the number of waves passing through $1 \text{ m}$ length is . . . . . . .

All components of the electromagnetic spectrum in vacuum have the same

In an $EM$ wave,the amplitude of the magnetic field $H_0$ and the amplitude of the electric field $E_0$ at any place are related as:

Consider the following:
$I.$ Waves created on the surfaces of a water pond by a vibrating source.
$II.$ Wave created by an oscillating electric field in air.
$III.$ Sound waves travelling under water.
Which of these can be polarized?

The speed of electromagnetic waves is the same for all ........

If an optical medium possesses a relative permeability of $\frac{10}{\pi}$ and relative permittivity of $\frac{1}{0.0885}$,then the velocity of light is greater in vacuum than that in this medium by . . . . . . times. $\left(\mu_0=4 \pi \times 10^{-7} \ H/m, \varepsilon_0=8.85 \times 10^{-12} \ F/m, c=3 \times 10^8 \ m/s\right)$