Question

A plane electromagnetic wave travels in vacuum along z-direction. What can you say about the directions of its electric and magnetic field vectors? If the frequency of the wave is 30 MHz, what is its wavelength?

Answer 1

The electromagnetic wave travels in a vacuum along the z-direction. The electric field (E) and the magnetic field (H) are in the x-y plane. They are mutually perpendicular.
Frequency of the wave, $ν = 30 \ MHz$ =$30 \times 10^6 s^{−1 }$
Speed of light in a vacuum, $c = 3 \times 10^8 \ m/s$
Wavelength of a wave is given as:

$λ = \frac cv$

$λ = \frac {3 \times 10^8}{30 \times 10^6}$

$λ = 10\ m$