Editing Frequency (section)

== Definitions and units {{anchor|Definitions|Units|Definition|Unit}} ==
[[File:Pendulum-no-text.gif|thumb|A [[pendulum]] with a period of 2.8&nbsp;s and a frequency of 0.36&nbsp;[[Hertz|Hz]]]]
For cyclical phenomena such as [[oscillation]]s, [[wave]]s, or for examples of [[simple harmonic motion]], the term ''frequency'' is defined as the number of cycles or repetitions per unit of time. The conventional symbol for frequency is ''f'' or ''ν'' (the Greek letter [[Nu (letter)|nu]]) is also used.{{sfn|Serway|Faughn|1989|p=346}} The ''period'' ''T'' is the time taken to complete one cycle of an oscillation or rotation. The frequency and the period are related by the equation{{sfn|Serway|Faughn|1989|p=354}}
<math display=block qid=Q11652>f = \frac{1}{T}.</math>

The term ''temporal frequency'' is used to emphasise that the frequency is characterised by the number of occurrences of a repeating event per unit time.

The [[SI]] unit of frequency is the [[hertz]] (Hz),{{sfn|Serway|Faughn|1989|p=354}} named after the German physicist [[Heinrich Hertz]] by the [[International Electrotechnical Commission]] in 1930. It was adopted by the [[CGPM]] (Conférence générale des poids et mesures) in 1960, officially replacing the previous name, ''[[cycle per second]]'' (cps). The SI unit for the period, as for all measurements of time, is the [[second]].<ref>{{cite web |title=Resolution 12 of the 11th CGPM (1960) |url=https://www.bipm.org/en/CGPM/db/11/12/ |publisher=BIPM (International Bureau of Weights and Measures) |access-date=21 January 2021 |archive-date=8 April 2020 |archive-url=https://web.archive.org/web/20200408155740/https://www.bipm.org/en/CGPM/db/11/12/ |url-status=dead }}</ref> A traditional unit of frequency used with rotating mechanical devices, where it is termed ''[[rotational frequency]]'', is [[revolution per minute]], abbreviated r/min or rpm.{{refn|{{cite journal|title=Special Publication 811: NIST Guide to the SI, Chapter 8|journal=NIST |date=28 January 2016 |url=https://www.nist.gov/pml/special-publication-811/nist-guide-si-chapter-8|access-date=2022-11-08}}}}  Sixty rpm is equivalent to one hertz.{{sfn|Davies|1997|p=275}}