Hertz (unit): Difference between revisions
imported>Bruce M. Tindall (Good old megacycles!) |
imported>Paul Wormer m (Hertz moved to Hertz (unit): There is also a person named Hertz) |
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The '''hertz''' is the [[SI]] unit of frequency, and has units of inverse [[second]]s. The hertz is used only for periodic phenomena.<ref>{{cite web|title=The International System of Units (SI)|publisher=BIPM|date=2006|url=http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf}}, p. 118</ref> The symbol of the hertz in SI is '''Hz'''. | The '''hertz''' is the [[SI]] unit of frequency, and has units of inverse [[second]]s. The hertz is used only for periodic phenomena.<ref>{{cite web|title=The International System of Units (SI)|publisher=BIPM|date=2006|url=http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf}}, p. 118</ref> The symbol of the hertz in SI is '''Hz'''. | ||
The hertz is named for [[Heinrich Hertz]] (1857 - 1894), an early pioneer in electromagnetic research and the first person to demonstrate the transmission of electromagnetic | The hertz is named for [[Heinrich Hertz]] (1857 - 1894), an early pioneer in electromagnetic research and the first person to demonstrate the transmission of [[electromagnetic wave]]s through space. | ||
The hertz is a derived unit in the SI, equal to 1 [[second|s]]<sup>-1</sup> (Hz = s<sup>-1</sup>). In pre-SI usage the unit was called "cycles," "cycles per second," or "cps," from which additional terms like "kilocycles" and "megacycles" (or "kc/s" and "mc/s") were derived. | The hertz is a derived unit in the SI, equal to 1 [[second|s]]<sup>-1</sup> (Hz = s<sup>-1</sup>). In pre-SI usage the unit was called "cycles," "cycles per second," or "cps," from which additional terms like "kilocycles" and "megacycles" (or "kc/s" and "mc/s") were derived. | ||
==Practical use== | ==Practical use== | ||
Household alternating electrical current is usually 50 Hz or 60 Hz. In the United States, commercial [[amplitude modulation|AM]] radio | Household alternating electrical current is usually 50 Hz or 60 Hz. In the United States, commercial [[amplitude modulation|AM]] radio broadcasting uses frequencies between 535 kHz and 1605 kHz (1.605 MHz), and commercial [[frequency modulation|FM]] radio broadcasting uses frequencies from 87.5 MHz to 107.7 MHz. Visible [[light]] has a frequency of about 400 THz to 750 THz. | ||
[[Sound]]s within the range of 20 Hz to 30 kHz are audible to humans, though as people age their ability to hear the highest frequencies diminishes. Automobile engines typically idle between 10 and 20 Hz. The earth rotates with a frequency of approximately 11.57 µHz (11.57 microhertz) | [[Sound]]s within the range of 20 Hz to 30 kHz are audible to humans, though as people age their ability to hear the highest frequencies diminishes. Automobile engines typically idle between 10 and 20 Hz. The earth rotates with a frequency of approximately 11.57 µHz (11.57 microhertz) | ||
Latest revision as of 04:14, 30 November 2009
The hertz is the SI unit of frequency, and has units of inverse seconds. The hertz is used only for periodic phenomena.[1] The symbol of the hertz in SI is Hz.
The hertz is named for Heinrich Hertz (1857 - 1894), an early pioneer in electromagnetic research and the first person to demonstrate the transmission of electromagnetic waves through space.
The hertz is a derived unit in the SI, equal to 1 s-1 (Hz = s-1). In pre-SI usage the unit was called "cycles," "cycles per second," or "cps," from which additional terms like "kilocycles" and "megacycles" (or "kc/s" and "mc/s") were derived.
Practical use
Household alternating electrical current is usually 50 Hz or 60 Hz. In the United States, commercial AM radio broadcasting uses frequencies between 535 kHz and 1605 kHz (1.605 MHz), and commercial FM radio broadcasting uses frequencies from 87.5 MHz to 107.7 MHz. Visible light has a frequency of about 400 THz to 750 THz.
Sounds within the range of 20 Hz to 30 kHz are audible to humans, though as people age their ability to hear the highest frequencies diminishes. Automobile engines typically idle between 10 and 20 Hz. The earth rotates with a frequency of approximately 11.57 µHz (11.57 microhertz)
Notes
- ↑ The International System of Units (SI). BIPM (2006)., p. 118