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History. Applications. Sound and vibration. Electromagnetic radiation. Computers. SI multiples. Unicode. See also. Notes. References. External links. Hertz. The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second.
Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz.
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From early in the 20th century, the radio frequency of 500 kilohertz (500 kHz) was an international calling and distress frequency for Morse code maritime communication. For much of its early history, this frequency was referred to by its equivalent wavelength, 600 meters, or, using the earlier frequency unit name, 500 kilocycles ...
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. Factor. ( Hz ) Multiple. Value.
Factor ( Hz )MultipleValueItem10 −181 attohertz (aHz)~2.2978 aHzThe Hubble constant (once in 13.8 billion ...10 −1710 aHz~79 aHzSupercontinent cycle (about every 400 ...10 −16100 aHz~137.8 aHzOnce per galactic year (about every 230 ...10 −151 femtohertz (fHz)~3 fHzSound waves created by a supermassive ...Low frequency ( LF) is the ITU designation [1] for radio frequencies (RF) in the range of 30–300 kHz. Since its wavelengths range from 10–1 km, respectively, it is also known as the kilometre band or kilometre wave s. LF radio waves exhibit low signal attenuation, making them suitable for long-distance communications.
Medium frequency ( MF) is the ITU designation [1] for radio frequencies (RF) in the range of 300 kilohertz (kHz) to 3 megahertz (MHz). Part of this band is the medium wave (MW) AM broadcast band. The MF band is also known as the hectometer band as the wavelengths range from ten to one hectometers (1000 to 100 m).
The commonly stated range of human hearing is 20 to 20,000 Hz. [5] [6] [note 1] Under ideal laboratory conditions, humans can hear sound as low as 12 Hz [7] and as high as 28 kHz, though the threshold increases sharply at 15 kHz in adults, corresponding to the last auditory channel of the cochlea. [8]
