Microsecond

A microsecond is a unit of time in the International System of Units (SI) equal to one millionth (0.000001 or 10⁻⁶ or 1⁄1,000,000) of a second. Its symbol is μs, sometimes simplified to us when Unicode is not available.

A microsecond is equal to 1000 nanoseconds or 1⁄1,000 of a millisecond. Because the next SI prefix is 1000 times larger, measurements of 10⁻⁵ and 10⁻⁴ seconds are typically expressed as tens or hundreds of microseconds.

Examples

• 1 microsecond (1 μs) – cycle time for frequency 1×10⁶ hertz (1 MHz), the inverse unit. This corresponds to radio wavelength 300 m (AM medium wave band), as can be calculated by multiplying 1 μs by the speed of light (approximately 3.00×10⁸ m/s).
• 1 microsecond – the length of time of a high-speed, commercial strobe light flash (see air-gap flash).
• 1 microsecond – protein folding takes place on the order of microseconds.
• 1.8 microseconds – the amount of time subtracted from the Earth's day as a result of the 2011 Japanese earthquake.^[1]
• 2 microseconds – the lifetime of a muonium particle
• 2.68 microseconds – the amount of time subtracted from the Earth's day as a result of the 2004 Indian Ocean earthquake.^[2]
• 3.33564095 microseconds – the time taken by light to travel one kilometre in a vacuum
• 5.4 microseconds – the time taken by light to travel one mile in a vacuum (or radio waves point-to-point in a near vacuum)
• 8.01 microseconds – the time taken by light to travel one mile in typical single-mode fiber optic cable
• 10 microseconds (μs) – cycle time for frequency 100 kHz, radio wavelength 3 km
• 18 microseconds – net amount per year that the length of the day lengthens, largely due to tidal acceleration.^[3]
• 20.8 microseconds – sampling interval for digital audio with 48,000 samples/s
• 22.7 microseconds – sampling interval for CD audio (44,100 samples/s)
• 38 microseconds – discrepancy in GPS satellite time per day (compensated by clock speed) due to relativity ^[4]
• 50 microseconds – cycle time for highest human-audible tone (20 kHz)
• 50 microseconds – to read the access latency for a modern solid state drive which holds non-volatile computer data^[5]
• 100 microseconds (0.1 ms) – cycle time for frequency 10 kHz
• 125 microseconds – common sampling interval for telephone audio (8000 samples/s)^[6]
• 164 microseconds – half-life of polonium-214
• 240 microseconds – half-life of copernicium-277
• 260 to 480 microseconds - return trip ICMP ping time, including operating system kernel TCP/IP processing and answer time, between two gigabit ethernet devices connected to the same local area network switch fabric.
• 277.8 microseconds – a fourth (a 60th of a 60th of a second), used in astronomical calculations by al-Biruni and Roger Bacon in 1000 and 1267 AD, respectively.^[7][8]
• 489.67 microseconds – time for light at a 1550 nm frequency to travel 100 km in a singlemode fiber optic cable (where speed of light is approximately 200 million metres per second due to its index of refraction).
• The average human eye blink takes 350,000 microseconds (just over 1⁄3 second).
• The average human finger snap takes 150,000 microseconds (just over 1⁄7 second).
• A camera flash illuminates for 1,000 microseconds.
• Standard camera shutter speed opens the shutter for 4,000 microseconds or 4 milliseconds.
• 584542 years of microseconds fit in 64 bits: (2**64)/(1e6*60*60*24*365.25)

See also

• International System of Units
• Jiffy (time)
• Orders of magnitude (time)
• Picosecond
• Millisecond

References

1. Gross, R.S. (14 March 2014). "Japan quake may have shortened Earth days, moved axis". JPL News. Jet Propulsion Laboratory. Retrieved 23 August 2019.
2. Cook-Anderson, Gretchen; Beasley, Dolores (January 10, 2005). "NASA Details Earthquake Effects on the Earth". NASA. Retrieved September 18, 2021.
3. MacDonald, Fiona. "Earth's Days Are Getting 2 Milliseconds Longer Every 100 Years". ScienceAlert. Retrieved 2017-03-08.
4. Richard Pogge. "GPS and Relativity". Retrieved 2011-10-01.
5. Intel Solid State Drive Product Specification
6. Kumar, Anurag; Manjunath, D.; Kuri, Joy (2008), "Application Models and Performance Issues", Wireless Networking, Elsevier, pp. 53–79, doi:10.1016/b978-012374254-4.50004-1, ISBN 978-0-12-374254-4, retrieved 2022-08-08
7. al-Biruni (1879). The chronology of ancient nations: an English version of the Arabic text of the Athâr-ul-Bâkiya of Albîrûnî, or "Vestiges of the Past". Translated by Sachau C Edward. W. H. Allen. pp. 147–149. OCLC 9986841.
8. R Bacon (2000) [1928]. The Opus Majus of Roger Bacon. translator: BR Belle. University of Pennsylvania Press. table facing page 231. ISBN 978-1-85506-856-8.

External links

• The National Institute of Standards and Technology (NIST)