THE polarization can be understood as the process of “filtering” waves, in which they are selected according to their vibration direction, after passing through a material that serves as a filter, called polarizer.
This is a phenomenon exclusive to cross waves, a type of wave that propagates perpendicular to the vibration. longitudinal waves, which have a propagation direction parallel to the vibration direction, cannot be polarized. O sound is a type of longitudinal wave and therefore cannot be polarized.
Polarization of electromagnetic waves
At electromagnetic waves are the result of propagation perpendicular to each other of a electric field and another magnetic, both variable in space and time. These variable fields propagate through space and give rise to electromagnetic waves. The waves produced by radio and TV broadcasters are polarized waves, as they present, in a certain direction, an electric field that varies in space and time. Sunlight is an example of an unpolarized electromagnetic wave as it is emitted by the source in different directions.
The following image shows an electromagnetic wave being polarized. Note that, initially, a light wave propagates, with its vertical and horizontal components, until reaching a vertical filter. After passing through this filter, only waves with vertical vibration direction pass through, so polarized light has this same vibration direction.
Note also that when the vertically polarized light reaches the second filter, placed horizontally, the vertical waves do not pass and, therefore, the light is prevented from propagating.
The following image shows a certain number of antennas from TV agglomerated. What do they all have in common?
All metal rods that make up the antennas in this image are horizontal. In the region where these antennas are located, the broadcasters TV transmit horizontally polarized waves, that is, the electric field of the television waves is oscillating horizontally. Thus, this electric field can produce, in the antennas, electric currents capable of providing a signal to the receivers of the television set.
At the Brazil it is us USA, the polarization is horizontal, so the antennas are presented as they appear in the image above. At England, on the other hand, the polarization is vertical, as the electric field oscillates vertically and, therefore, the antennas must be installed with their poles vertical.
By Joab Silas
Graduated in Physics
Source: Brazil School - https://brasilescola.uol.com.br/o-que-e/fisica/o-que-e-polarizacao.htm
