# Hertz

The hertz (symbol: Hz ) is the unit derived from Fréquence of the international Système (IF). It is equivalent to a Oscillation by second (S, 1/s).

Its name comes from the German Physicien Heinrich Rudolf Hertz which contributed important scientific shares to the field of the electromagnetism. As example, the red Lumière has a Fréquence approximately 4.6 {{x10 14}} Hz.

The term cps (cycles a second) is still sometimes met.

## Examples

The domestic electric current (sector) is a Alternative course: the polarity (about) of the terminals is reversed several times a second. The European standard, fixed at 50 Hz means 100 changes a second (each terminal is positive 50 times and negative 50 times each second) while the American standard, for its part fixed at 60 Hz, will show a change of polarity 120 times a second.

The height of a sound is measured (inter alia things) by the number of vibrations a second. The the of reference in music is obtained by the Diapason which oscillates to 440 Hz. It is also said that the human ear perceives the sounds in a beach of frequency between 20 Hz and 20,000 Hz.

The waves radios in Frequency modulation are diffused on a tape going of 88 MHz with 108 MHz.

The first personal computers (beginning of the Years 1980) had a frequency of clock of Processeur ranging between 1 and 8 MHz. A processor which has a basic cycle of 0.83 NS thus has a frequency of 1 (0.83 {{x10 - 9}} S) = 1.2 {{x10 9}} Hz = 1.2 GHz.

## Multiples (international System)

Simple: Hertz Zh-min-nan: Hz

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