Hertz
:''For the radio pioneer, see
Heinrich Rudolf Hertz. For other uses, see
Hertz (disambiguation).The
hertz (symbol: Hz) is the
SI unit of
frequency. In English,
hertz is used as both singular and plural.
One hertz is defined as the
reciprocal second.
1 Hz = 1 s
−1One hertz simply means "one per
second" (1 / s); 100 Hz means "one hundred per second", and so on. The unit may be applied to any periodic event – for example, a clock might be said to tick at 1 Hz, or a human heart might be said to
beat at 1.2 Hz. Frequency of aperiodic events, such as radioactive decays, is expressed in
becquerels.
To avoid confusion, periodically varying angles are typically
not expressed in hertz, but rather in an appropriate angular unit such as
radians per second. A disc rotating at 1 revolution per minute (RPM) can thus be said to be rotating at 0.105 rad/s
or 0.017 Hz, where the latter reflects the number of
complete revolutions per second.
The hertz is named after the
German physicist
Heinrich Rudolf Hertz, who made important scientific contributions to
electromagnetism. The name was established by the IEC in 1930 [
1]. It was adopted by the
CGPM (
Conférence générale des poids et mesures) in 1960, replacing the previous name for the unit,
cycles per second (cps), along with its related multiples, primarily
kilocycles (kc) and
megacycles (Mc). Hertz largely replaced cycles in common use by 1970.
*
Acoustics*
Electromagnetic spectrum*
Radio frequency*
Frequency converter*
Wavelength*
Orders of magnitude (frequency)
