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The electromagnetic spectrum is the full range of electromagnetic radiation, organized by frequency or wavelength. The spectrum is divided into separate bands, with different names for the electromagnetic waves within each band. From low to high frequency these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and ...
Extremely low frequency (ELF) is the ITU designation [1] for electromagnetic radiation (radio waves) with frequencies from 3 to 30 Hz, and corresponding wavelengths of 100,000 to 10,000 kilometers, respectively. [2][3] In atmospheric science, an alternative definition is usually given, from 3 Hz to 3 kHz. [4][5] In the related magnetosphere ...
Orders of magnitude (frequency) The following list illustrates various frequencies, measured in hertz, according to decade in the order of their magnitudes, with the negative decades illustrated by events and positive decades by acoustic or electromagnetic uses. Acoustic – frequency of G −7, the lowest note sung by the singer with the ...
Letter frequency is the number of times letters of the alphabet appear on average in written language. Letter frequency analysis dates back to the Arab mathematician Al-Kindi (c. 801 –873 AD), who formally developed the method to break ciphers. Letter frequency analysis gained importance in Europe with the development of movable type in 1450 ...
The frequency boundaries of the radio spectrum are a matter of convention in physics and are somewhat arbitrary. Since radio waves are the lowest frequency category of electromagnetic waves, there is no lower limit to the frequency of radio waves. [4] Radio waves are defined by the ITU as: "electromagnetic waves of frequencies arbitrarily lower than 3000 GHz, propagated in space without ...
Hearing range describes the frequency range that can be heard by humans or other animals, though it can also refer to the range of levels. The human range is commonly given as 20 to 20,000 Hz, although there is considerable variation between individuals, especially at high frequencies, and a gradual loss of sensitivity to higher frequencies ...
Vocal range. Vocal range is the range of pitches that a human voice can phonate. A common application is within the context of singing, where it is used as a defining characteristic for classifying singing voices into voice types. [1] It is also a topic of study within linguistics, phonetics, and speech-language pathology, particularly in ...
The original frequency allocation in North America used by Edwin Armstrong used the frequency band from 42 through 50 MHz, but this allocation was changed to a higher band beginning in 1945. In Canada, the United States, Mexico, the Bahamas, etc., there are 101 FM channels numbered from 200 (center frequency 87.9 MHz) to 300 (center frequency 107.9 MHz), though these numbers are rarely used ...