Microsecond
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Microsecond
This animation illustrates the generation of the debris and ejecta clouds after a spherical aluminum projectile impacts a thin aluminum plate at approximately 7 km/s. The frame interval is about 1 microsecond.

A microsecond is an SI unit of time equal to one millionth (0.000001 or 10-6 or ​) of a second. Its symbol is ?s, 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 ?s) - 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 ?s by the speed of light (approximately ).
• 1 microsecond - the length of time of a high-speed, commercial strobe light flash (see air-gap flash).
• 1.8 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 kilometer 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 (?s) - 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 - sampling interval for telephone audio (8000 samples/s)
• 164 microseconds - half-life of polonium-214
• 240 microseconds - half-life of copernicium-277
• 250 microseconds - cycle time for highest tone in telephone audio (4 kHz)[]
• 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]
• 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 meters 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)

## References

1. ^ Gross, R.S. (14 March 2014). "Japan quake may have shortened Earth days, moved axis". JPL News. Jet Propulsion Laboratory. Retrieved 2019.
2. ^ Buis, Alan (January 10, 2005). "NASA Details Earthquake Effects on the Earth". NASA. Retrieved 2011.
3. ^ MacDonald, Fiona. "Earth's Days Are Getting 2 Milliseconds Longer Every 100 Years". ScienceAlert. Retrieved .
4. ^ Richard Pogge. "GPS and Relativity". Retrieved .
5. ^ Intel Solid State Drive Product Specification
6. ^ 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.
7. ^ 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.