SI second

E116185
SI base unit coherent SI unit unit of time

The SI second is the base unit of time in the International System of Units, precisely defined by a fixed number of periods of radiation corresponding to a specific transition in the cesium-133 atom.

Try in SPARQL Jump to: Surface forms Statements Referenced by

All labels observed (2)

Label Occurrences
SI second canonical 4
second 1

Statements (48)

Predicate Object
instanceOf SI base unit ⓘ
coherent SI unit ⓘ
unit of time ⓘ
baseQuantity time ⓘ
belongsToCategory base units of the SI ⓘ
category time standard ⓘ
constantExactness exact by definition ⓘ
constantExactValue 9192631770 Hz ⓘ
constantName cesium-133 hyperfine transition frequency ⓘ
constantSymbol Δν(Cs) ⓘ
countInDayApprox 86400 ⓘ
definedBy cesium-133 hyperfine transition ⓘ
unperturbed ground-state hyperfine transition of the cesium-133 atom ⓘ
definedIn 13th CGPM resolution 1 (1967) ⓘ
definingBody General Conference on Weights and Measures ⓘ
definingBodyAbbreviation General Conference on Weights and Measures ⓘ
surface form: CGPM
definitionEpoch 1967 ⓘ
definitionText The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the unperturbed ground state of the cesium-133 atom. ⓘ
dependsOnConstant Δν(Cs) ⓘ
dimensionSymbol T ⓘ
dimensionVector T1 ⓘ
governingOrganization International Bureau of Weights and Measures ⓘ
governingOrganizationAbbreviation International Bureau of Weights and Measures ⓘ
surface form: BIPM
hasMultiple day ⓘ
hour ⓘ
microsecond ⓘ
millisecond ⓘ
minute ⓘ
nanosecond ⓘ
picosecond ⓘ
isBaseOf SI derived units involving time ⓘ
isRealizedBy cesium atomic clocks ⓘ
primary frequency standards ⓘ
note no prefix is used with the second to form minute, hour, or day ⓘ
numericalValueOfTransitionFrequency 9192631770 ⓘ
predecessorUnit ephemeris second ⓘ
reaffirmedIn 26th General Conference on Weights and Measures ⓘ
surface form: 26th CGPM (2018)
relatedStandard ISO 80000-3 ⓘ
replacedDefinitionOf mean solar second ⓘ
symbol s ⓘ
system International System of Units ⓘ
transitionFrequencyUnit hertz ⓘ
usedFor measuring duration ⓘ
measuring time intervals ⓘ
usedIn GPS timekeeping ⓘ
International Atomic Time ⓘ
atomic time scales ⓘ
Coordinated Universal Time ⓘ
surface form: coordinated universal time

Referenced by (5)

Full triples — surface form annotated when it differs from this entity's canonical label.

International Atomic Time → definedBy → SI second ⓘ
TAI → basedOn → SI second ⓘ
cesium atomic clocks → defines → SI second ⓘ
Terrestrial Time → timeUnit → SI second ⓘ
Restatement (Second) of Contracts → editionNumber → SI second ⓘ
this entity surface form: second