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hertz

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The unit of frequency in SI. A measurement in hertz of a periodic phenomenon’s frequency is the number of periods in 1 second. Symbol, Hz. The plural is also “hertz”, not “hertzes”.

The hertz was adopted by the 11ᵗʰ CGPM (1960) in Resolution 12, which introduced SI. It replaced cycles per second.

The hertz was named for H. R. Hertz (1857 – 1894).