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10-27

activity

URNurn:iso:std:iso:80000:-10:ed-2:en:item:10-27

https://metanorma.github.io/isq-smart/quantities/part-10/t10-27
urn:iso:std:iso:80000:-10:ed-2:en:item:10-27

ISQ Identifiers

ISO

urn:iso:std:iso:80000:-10:ed-2:en:item:10-27

IEC

urn:iec:std:iec:80000-10:2019:::item:10-27

Designations

ENactivity

FRactivité

Symbol

A

Notation systems

Rendered

A

AsciiMath

A

LaTeX

A

Definition

differential quotient of $N$ with respect to time, where $N$ is the mean change in the number of nuclei in a particular energy state due to spontaneous nuclear transformations in a time interval of duration (ISO 80000-3: Space and time) $d t$ :

A = - \frac{d N}{d t}

quotient différentiel de $N$ par rapport au temps, où $N$ est la variation moyenne du nombre de noyaux dans un état d'énergie particulier due à des transformations nucléaires spontanées dans un intervalle de temps de durée (ISO 80000-3: Space and time) $d t$ :

A = - \frac{d N}{d t}

Units

B q

becquerel

View related quantities →

s^{- 1}

per second

View related quantities →

Notes

For exponential decay, $A = λ N$ , where $λ$ is the decay constant (decay constant).

The becquerel ( $unitsml(Bq)$ ) is a special name for second to the power minus one, to be used as the coherent SI unit of activity.

In report 85a of the ICRU a definition with an equivalent meaning is given as: The activity, $A$ , of an amount of a radionuclide in a particular energy state at a given time is the quotient of $- d N$ by $d t$ , where $d N$ is the mean change in the number of nuclei in that energy state due to spontaneous nuclear transformations in the time interval $d t$ :

A = - \frac{d N}{d t}

Referenced by

specific activity activity density surface-activity density

Concept HierarchyPendrill (2024)

T⁻¹frequency-type quantitiesLevel 0 · Kind

Broader concepts

◇ frequency-type quantities

Narrower concepts

↓ specific activity

Characterizes

● radionuclide

Ontology
isq:Quantity smart:TermEntry

Class Hierarchy

smart:Entity smart:TermEntryisq:Quantity

A physical quantity as defined in ISO/IEC 80000, with associated symbols, definitions, and units of measurement.

Instance IRI

isq:t10-27

Properties

isq:QuantityShape

Property	Value
rdf:type	isq:Quantity smart:TermEntry
dcterms:identifier	10-27
skosxl:prefLabel	"activity"@en
skosxl:altLabel	"A"@en
skos:definition	differential quotient of stem:[N] with respect to time, where stem:[N] is the mean change in the number of nuclei in a p…
skos:note	For exponential decay, stem:[A = lambda N], where stem:[lambda] is the decay constant (<<t10-24>>). The becquerel (stem…
isq:hasUnit	Bq (becquerel)s^(-1) (per second)
isq:hasDimension	isq:Dimension
smart:hasBindingnessType	bindingness-type:normative
dcterms:isPartOf	isq:part-10

Related Entities

isq:QuantityShape isq:part-10 isq:Unit isq:Dimension isq:hasDimension smart:TermEntry