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A unit of time is any particular time interval, used as a standard way of measuring or expressing duration. The base unit of time in the International System of Units (SI), and by extension most of the Western world , is the second , defined as about 9 billion oscillations of the caesium atom.
10 −14 qs: The length of one Planck time (t P = / ≈ 5.39 × 10 −44 s) [3] is the briefest physically meaningful span of time. It is the unit of time in the natural units system known as Planck units. 10 −30: quectosecond: qs Quectosecond, (quecto-+ second), is one nonillionth of a second 10 −27: rontosecond: rs
The measurement of time is unique in SI in that while the second is the base unit, and measurements of time smaller than a second use prefixed units smaller than a second (e.g. microsecond, nanosecond, etc.), measurements larger than a second instead use traditional divisions, including the sexagesimal-based minute and hour as well as the less ...
The earliest technical usage for jiffy was defined by Gilbert Newton Lewis (1875–1946). He proposed in 1926 a unit of time called the "jiffy" which was equal to the time it takes light to travel one centimeter in vacuum (approximately 33.3564 picoseconds). [5]
In the International System of Units (SI), the unit of time is the second (symbol: s). It has been defined since 1967 as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium 133 atom", and is an SI base unit. [12]
The svedberg (S or Sv) is a unit of time used in chemistry equal to one hundred femtoseconds (100 fs). The shake is a unit of time used in nuclear physics equal to ten nanoseconds (10 ns). The sigma is a unit of time equal to one microsecond (1 μs). The jiffy is sometimes used to mean a unit of time of 10 ms. [dubious – discuss]
This category identifies units of time, either general (in Chronology) or for specific scientific and other uses; and some closely related notions. The main article for this category is Unit of time .
A millisecond (from milli-and second; symbol: ms) is a unit of time in the International System of Units equal to one thousandth (0.001 or 10 −3 or 1 / 1000) of a second [1] [2] or 1000 microseconds. A millisecond is to one second, as one second is to approximately 16.67 minutes.