Microsecond Explained

microsecond
Symbol:	μs
Standard:	SI
Quantity:	time
Units1:	SI units

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

A microsecond is equal to 1000 nanoseconds or 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 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).
• 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 (thus this is the speed of carbon-based life).
• 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 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).
• 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.^{[6] [7]}
• 490 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 second).
• The average human finger snap takes 150,000 microseconds (just over 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

External links

• The National Institute of Standards and Technology (NIST)

Notes and References

1. News: Gross . R.S. . Japan quake may have shortened Earth days, moved axis . 23 August 2019 . Jet Propulsion Laboratory . JPL News . 14 March 2014.
2. Web site: NASA Details Earthquake Effects on the Earth . NASA . January 10, 2005 . September 18, 2021 . Cook-Anderson . Gretchen . Beasley . Dolores.
3. News: Earth's Days Are Getting 2 Milliseconds Longer Every 100 Years. MacDonald. Fiona. ScienceAlert. 2017-03-08. en-gb.
4. Web site: GPS and Relativity . 2011-10-01 . Richard Pogge .
5. http://www.intel.com/content/dam/www/public/us/en/documents/product-specifications/ssd-dc-s3500-spec.pdf Intel Solid State Drive Product Specification
6. Book: al-Biruni . al-Biruni . Sachau C Edward . 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" . 147–149 . . 9986841.
7. Book: R Bacon . Roger Bacon . translator: BR Belle . 2000 . 1928 . . . table facing page 231 . 978-1-85506-856-8 . true.