Editing Hertz

The '''hertz''' (symbol: Hz) is the [[SI]] unit of [[frequency]]. It is named in honor of the [[Germany|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<sup>&minus;1</sup>

==SI multiples==
{|class="wikitable"
! Multiple
! Name
! Symbol
!
! Multiple
! Name
! Symbol
|-
|10<sup>0</sup>
| '''hertz'''
|Hz
|
|&nbsp;
|&nbsp;
|&nbsp;
|-
|10<sup>1</sup>
| decahertz  
|daHz
|
|10<sup>−1</sup>
| decihertz  
|dHz
|-
|10<sup>2</sup>
| hectohertz 
| hHz
|
|10<sup>−2</sup>
| centihertz 
| cHz
|-
|10<sup>3</sup>
| kilohertz  
|kHz
|
|10<sup>−3</sup>
| millihertz 
| mHz
|-
|10<sup>6</sup>
| megahertz  
|MHz
|
|10<sup>−6</sup>
| microhertz 
| µHz
|-
|10<sup>9</sup>
| gigahertz  
|GHz
|
|10<sup>−9</sup>
| nanohertz  
|nHz
|-
|10<sup>12</sup>
| terahertz  
|THz
|
|10<sup>−12</sup>
| picohertz  
|pHz
|-
|10<sup>15</sup>
| petahertz  
|PHz
|
|10<sup>−15</sup>
| femtohertz  
|fHz
|-
|10<sup>18</sup>
| exahertz  
|EHz
|
|10<sup>−18</sup>
| attohertz  
|aHz
|-
|10<sup>21</sup>
| zettahertz 
| ZHz
|
|10<sup>−21</sup>
| zeptohertz 
| zHz
|-
|10<sup>24</sup>
|yottahertz
|YHz
|
|10<sup>−24</sup>
| yoctohertz
| yHz
|-
|}

==Explanation==
One hertz simply means "one per [[second]]" (1 / s); 100&#160;Hz means "one hundred per second", and so on. The unit may be applied to any periodic event &ndash; for example, a [[clock]] might be said to tick at 1&#160;Hz, or a human heart might be said to [[heart rate|beat]] at 1.2&nbsp;Hz. Frequency of random events, such as [[radioactive decay]]s, is expressed in [[becquerel]]s.

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)]]

{{enWP|Hertz}}
[[Category:SI derived units]]
[[Category:Units of frequency]]