Hertz

The hertz (symbol: Hz) is the SI unit of frequency. It is named in honor of the German physicist Heinrich Rudolf Hertz who made important scientific contributions to electromagnetism.

Definition

One hertz is defined as one cycle per second.

1 Hz = 1 s⁻¹

SI multiples

Multiple	Name	Symbol		Multiple	Name	Symbol
100	hertz	Hz
101	decahertz	daHz		10−1	decihertz	dHz
102	hectohertz	hHz		10−2	centihertz	cHz
103	kilohertz	kHz		10−3	millihertz	mHz
106	megahertz	MHz		10−6	microhertz	µHz
109	gigahertz	GHz		10−9	nanohertz	nHz
1012	terahertz	THz		10−12	picohertz	pHz
1015	petahertz	PHz		10−15	femtohertz	fHz
1018	exahertz	EHz		10−18	attohertz	aHz
1021	zettahertz	ZHz		10−21	zeptohertz	zHz
1024	yottahertz	YHz		10−24	yoctohertz	yHz

Explanation

One 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 random events, such as radioactive decays, is expressed in becquerels.

The name hertz 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.

See also

• Acoustics
• Electromagnetic spectrum
• Radio frequency
• Wavelength
• Orders of magnitude (frequency)