![]() The abbreviation AM stands for amplitude modulation, which is the method for placing information on these waves. Shorter wavelengths do not penetrate to any significant depth.ĪM radio waves are used to carry commercial radio signals in the frequency range from 540 to 1600 kHz. ![]() Very long wavelength radio waves are needed to reach this submarine, requiring extremely low frequency signals (ELF). Since salt water is a good conductor, radio waves are strongly absorbed by it, and very long wavelengths are needed to reach a submarine under the surface. The ability of radio waves to penetrate salt water is related to their wavelength (much like ultrasound penetrating tissue)-the longer the wavelength, the farther they penetrate. Recent reports that have looked at many European and American epidemiological studies have found no increase in risk for cancer due to exposure to \(E\)-fields.Įxtremely low frequency (ELF) radio waves of about 1 kHz are used to communicate with submerged submarines. But demographic data are either inconclusive or simply do not support the hazard theory. Some people suspect that living near such transmission lines may cause a variety of illnesses, including cancer. There is an ongoing controversy regarding potential health hazards associated with exposure to these electromagnetic fields ( \(E\)-fields). This high-voltage traction power line running to Eutingen Railway Substation in Germany radiates electromagnetic waves with very long wavelengths. (See this figure.) These extremely long wavelength electromagnetic waves (about 6000 km!) are one means of energy loss in long-distance power transmission. The lowest commonly encountered radio frequencies are produced by high-voltage AC power transmission lines at frequencies of 50 or 60 Hz. There are many uses for radio waves, and so the category is divided into many subcategories, including microwaves and those electromagnetic waves used for AM and FM radio, cellular telephones, and TV. They are created by many astronomical phenomena, and their study has revealed much about nature on the largest scales. Radio waves from outer space, for example, do not come from alien radio stations. The name is applied to electromagnetic waves of similar frequencies regardless of source. Its name derives from their most common use as a carrier of audio information (i.e., radio). The broad category of radio waves is defined to contain any electromagnetic wave produced by currents in wires and circuits.
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