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Bookmark or Share- How Do You Measure a Second? - NISTCesium atoms absorb microwaves with a frequency of 9,192,631,770 cycles per second, which then defines the international scientific unit for time, the second. The answer to how we measure time may seem obvious. We do so with clocks.
- Second - WikipediaThe second, symbol s, is the SI unit of time. It is defined by taking the fixed numerical value of the caesium frequency, Δν Cs, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 when expressed in the unit Hz, which is equal to s −1.
- What is a Second Unit Director & What Does a Second Unit Do? - StudioBinderA 2nd unit director is in charge of a film’s secondary crew and a second camera unit that shoots scenes separately from the main unit during principal photography. The 2nd unit director works under the film’s main director and often has no involvement in the main crew.
- Second | Measurement, Timekeeping, Clock | Britannicasecond, fundamental unit of time, now defined in terms of the radiation frequency at which atoms of the element cesium change from one state to another. The second was formerly defined as 1/86,400 of the mean solar day—i.e., the average period of rotation of the Earth on its axis relative to the Sun. In the mid-20th century this definition ...
- How long is a second? - Live ScienceThere are 24 hours in a day, 60 minutes in an hour, and 60 seconds in a minute — so surely a second is just 1/(24 x 60 x 60), or 1/86400, of a day, right? Well, it turns out that defining time ...
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