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Microsecond

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

A microsecond is to one second, as one second is to approximately 11.57 days.

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

Examples

  • 1 microsecond (1 μs) – cycle time for frequency (1&nbsp;MHz), the inverse unit. This corresponds to radio wavelength 300 m (AM medium wave band), as can be calculated by multiplying 1&nbsp;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.
  • 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.
  • 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.
  • 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.
  • 50 microseconds – cycle time for highest human-audible tone (20&nbsp;kHz).
  • 50 microseconds – to read the access latency for a modern solid state drive which holds non-volatile computer data.
  • 100 microseconds (0.1&nbsp;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.
  • 490 microseconds – time for light at a 1550&nbsp;nm frequency to travel 100&nbsp;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 or 1 millisecond.
  • Standard camera shutter speed opens the shutter for 4,000 microseconds or 4 milliseconds.
  • 584554 years of microseconds fit in 64 bits: (2**64)/(1e6*60*60*24*365.2425).

See also

References

External links