Electricity & Megnetism

Radio waves

Radio waves are a type of electromagnetic wave whose frequencies are lower than microwave and infrared frequencies. The frequencies corresponding to radio waves range between 3 kilohertz (3 kHz or 3.10³ Hz) and 300 gigahertz (300 GHz or 300.109 Hz) . Because they are electromagnetic waves, radio waves are capable of propagating in a vacuum at the speed of light .

History and characteristics of radio waves

The existence of radio waves was mathematically predicted by James Clerk Maxwell (1831-1879), however, the artificial production and detection of this type of waves only took place in 1887, thanks to experiments conducted by the German physicist Heinrich Hertz (1857-1894). ), such experiments helped to prove the wave nature of electromagnetic radiation .

The first fully functional radio wave transmitter was developed by the Italian Guglielmo Marconi (1874-1937), around 1895 , and went on sale in the mid-1900s.

 

Radio waves correspond to a wide range of frequencies in the electromagnetic spectrum , these waves carry even less energy than infrared waves, known as heat waves. Within the broad spectrum of radio waves, there is a subdivision . If you want to learn more about other electromagnetic waves, visit: electromagnetic spectrum .

Technological uses of radio waves

The technological applications that make use of radio waves are numerous and quite varied. The following table shows some of these applications, according to the order of magnitude of the radio wave frequency. Watch:

 

use Frequency order of magnitude
radars 10 GHz
Satellites (GPS) 1 GHz
mobile telephony 500 MHz
digital TV 300 MHz
FM radio 100 MHz
AM radio 1 MHz

Like all other electromagnetic waves, radio waves can propagate through a vacuum at the speed of light, and can be used to carry a large amount of information to radio antennas, television, GPS , mobile telephony and others.

Artificially produced radio waves are generated by accelerating electrical charges inside transmitting antennas. In nature, radio waves are generated during lightning strikes and also by celestial bodies such as the Sun and other stars .

Due to the large number of telecommunication devices that make use of radio frequencies, the emission of this type of waves is regulated by national and international laws, in order to reduce the possibility of interference between different signals.

Biological effects of radio waves

Radio waves are classified as non  ionizing radiation, the main effect of the interaction of radio waves with matter is heating: these waves can cause polar molecules (which show charge separation) to oscillate in the direction of the electromagnetic field, thus causing the temperature to rise. Want to know more about radiation? Access our text on ionizing radiation .

Radio waves are not able to carry the amount of energy that is needed to rip electrons from atoms, when this occurs it is possible for some chemical bonds to be broken, causing damage to DNA strands and possibly genetic mutations.

In addition to being used in telecommunications , radio waves are also used in oncological treatments , which promote the heating of cancer cells, destroying them thanks to the increase in temperature.

Although there is no evidence that radio waves can harm humans or even other animals, there are international guidelines that limit the intensity of radiation that can be emitted by sources of radio waves, such as mobile phones or television antennas, however, there is evidence that prolonged exposure of the human eye to 3000 MHz radio waves can result in cataracts , a disease that causes the lens to become cloudy, making it difficult for light to pass into the eye.

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