Frequency

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Frequency is the measurement of the number of times that a repeated event occurs per unit time. To calculate the frequency of an event, the number of occurrences of the event within a fixed time interval are counted, and then divided by the length of the time interval.

Related Topics:
Measurement - Time

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In SI units, the result is measured in hertz (Hz), named after the German physicist Heinrich Rudolf Hertz. 1 Hz means that an event repeats once per second, 2 Hz is twice per second, and so on. This unit was originally called a cycle per second (cps), which is still used sometimes. Other units that are used to measure frequency include revolutions per minute (rpm) and radians per second (rad/s). Heart rate and musical tempo are measured in beats per minute (BPM).

Related Topics:
SI - Hertz (Hz) - Heinrich Rudolf Hertz - Second - Revolutions per minute - Radians per second - Heart rate - Tempo - Beats per minute

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An alternative method to calculate frequency is to measure the time between two consecutive occurrences of the event (the period) and then compute the frequency as the reciprocal of this time:

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:f = rac{1}{T}

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where T is the period. A more accurate measurement takes many cycles into account and averages the period between each.

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