What are radio waves?
Radio waves are an invisible form of electromagnetic radiation (EMR), which differs in a wavelength from approximately 0.04 inches (one millimeter) to more than 62,000 miles (100,000 km), making it one of the widest ranges in the electromagnetic spectrum. "Radio" is a term describing all EMR forms with a wavelength longer than 0.04 inches (one millimeter) and a frequency below 300 GHz. It is formed by moving an electric charge that can result from electric current or random movement of atoms and molecules. This form of EMR is essential for human communication and is used for television, radio and mobile phones, as well as in radar and astronomy.
How radio waves are made
All electromagnetic radiation can be considered waves that with undulating electromagnetic field, such as the waves in the pond. They are produced when electrically charged particles, usually electron, change the speed or direction of movement. This can happen several ways such as heating atoms and molecules and changes in the level of EnerGIE electrons; Waves generated by radio transmitters are the result of electric current flow. The frequency and wavelength depend on the amount of energy involved with higher frequencies and shorter wavelengths indicating higher energy. If energy change is relatively small, radio waves can be produced.
uses
The best known use of radio waves is to send images, sound and text in the form of signals-long wavelength of the radio allows you to circumvent obstacles and travel long distances, unlike visible light and other higher frequency radiation. The atmosphere is absorbed by radio waves with a wavelength less than about 10 meters. Longer waves are reflected back and forth between the ionosphere and the ground, which makes the radio ideal for transmission through the horizon. The lowest frequencies are used with submarines, because of their low energy - for secrecy - and high penetrating power. These lower frequencies can be consideredObserve for more "bass", which means that they penetrate further, especially through thick media, such as water.
If you want to send information using radio waves, it must be coded in some way. There are two main methods known as amplitude modulation (AM) and frequency modulation (FM). In AM, the information is encoded by changing the amplitude or height of the wave, while the FM method includes the use of frequency changes to carry data. Patterns of different amplitude or frequencies are decoded where they are accepted to reproduce the original information, which can be images, sounds or text. In this way, complex information can be transmitted cheaply over long distances.
Radio astronomy is a vital tool for understanding the universe. Due to the existence of gas and dust clouds in galaxies, there is a limit of information of tklobouky can be obtained using visible light or higher EMR frequencies. However, radio waves can go through these obstacles and most of what they have learned about the interiorsGalaxy, underwent a analysis of natural radio sources. Astronomers also managed to detect radiation from the Big Bang itself, which was stretched from its initial very high frequencies to the microwave - called cosmic radiation in the background (CMB).
Health effects
were concerned about the possible impact on the health of the radio wool exposure, especially those in the microwave, used by mobile phones and radar. When radiation radiation is absorbed by tissue, it can cause heating. Normal exposure does not seem to cause any problems, but to be in close proximity to a strong radar transmitter can be potentially dangerous. The eye lens is particularly susceptible to heating dams and excessive microwave exposure could lead to cataracts. There are also concerns about long -term effects of frequent use of mobile phones, but since 2013 clinical studies have been inconclusive.
History
rJames Clerk Maxwell, who came up with equations for electromagnetism, later known as Maxwell's equation, was first predicted in 1865. When working on the relationship between electromagnetism and light, he realized that other forms of electromagnetic radiation with wavelengths above and below the visible range were possible. The existence of radiation with a lower wavelength was experimentally demonstrated 22 years later, in 1887, when Heinrich Hertz created radio waves in his laboratory. Over the past few decades, they have been widely used to transmit information. Guglielmo Marconi and Nikola Tesla are attributed with early pioneers in the radio area, but Marconi patented the first wireless telegraphic system in 1896.