Frequency

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Frequency
A pendulum making 25 complete oscillations in 60 s, a frequency of 0.416 Hz
Common symbols	f, ν
SI unit	hertz (Hz)
Other units	cycle per second (cps) revolution per minute (rpm or r/min)
In SI base units	s−1
Derivations from other quantities	f = 1 / T
Dimension	${\displaystyle {\mathsf {T}}^{-1}}$

Frequency is the number of occurrences of a repeating event per unit of time.^[1] Frequency is an important parameter used in science and engineering to specify the rate of oscillatory and vibratory phenomena, such as mechanical vibrations, audio signals (sound), radio waves, and light.

The interval of time between events is called the period. It is the reciprocal of the frequency.^[2] For example, if a heart beats at a frequency of 120 times per minute (2 hertz), its period is one half of a second.

Special definitions of frequency are used in certain contexts, such as the angular frequency in rotational or cyclical properties, when the rate of angular progress is measured. Spatial frequency is defined for properties that vary or cccur repeatedly in geometry or space.

The unit of measurement of frequency in the International System of Units (SI) is the hertz, having the symbol Hz.