# Definition:Frequency (Physics)

## Definition

Let $\map f t$ be a periodic function of time $t$.

The frequency of $f$ is the number of periods of $f$ that occur during a unit time interval.

## Dimension

The dimension of measurement of frequency is: $T^{-1}$.

## Units

The SI unit of measurement of frequency is the hertz $\mathrm {Hz}$:

$1 \ \mathrm {Hz} = 1 \ \mathrm{s}^{-1}$

that is, $1$ per second of time.