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A microsecond is an SI unit of time equal to one millionth (10^{−6} or ^{1}/_{1,000,000}) of a second. Its symbol is μs. One microsecond is to one second as one second is to 11.574 days.
A microsecond is equal to 1000 nanoseconds or ^{1}/_{1,000}milliseconds. Because the next SI unit is 1000 times larger, measurements of 10^{−5} and 10^{−4} seconds are typically expressed as tens or hundreds of microseconds.
1 microsecond (1 μs) – cycle time for frequency 1×10^{6}hertz (1 MHz), the inverse unit. This corresponds to radio wavelength 300m (AM mediumwave band), as can be calculated by multiplying 1 µs by the speed of light (approximately 300×10^{6} m/s) to determine the distance travelled.
1 microsecond – the length of time of a high-speed, commercial strobe light flash (see air-gap flash).
250 microseconds – cycle time for highest tone in telephone audio (4 kHz)^{[citation needed]}
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.^{[4]}^{[5]}
For reference[edit]
The average human eye blink takes 350,000 microseconds (just over 1/3 of one second).
The average human finger click takes 150,000 microseconds (just over 1/7 of one second).