Thehertz(symbolHz) is the unit offrequencyin theInternational System of Units(SI). It is defined as the number ofcycles per secondof a periodic phenomenon.[1]One of its most common uses is the description of thesine wave, particularly those used inradioand audio applications, such as the frequency of musical tones. The unit is named forHeinrich Rudolf Hertz, who was the first to conclusively prove the existence of electromagnetic waves.


Lights flash atfrequency f= 0.5 Hz (Hz = hertz), 1.0 Hz or 2.0 Hz, where

Hzmeans

flashes per second. T is theperiodand T =

s(s= seconds) means that

is the number of seconds per flash. T andfare each other'sreciprocal:f= 1/TandT = 1/f.