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Frequency Formula Physics

In this article learn about the frequency formula used in physics. Frequency is an important concept that is used a lot in science and engineering.
Here in this article, we will be learning about the temporal frequency formulas. Term Temporal frequency is used in order to distinguish it from spatial frequency.

What is Frequency

Temporal frequency specifies the rate of change observed in oscillatory or periodic phenomena (ex. mechanical vibrations, radio waves etc. ) with respect to time. It is basically the number of occurrences of a repeating event per unit of time.
Now that we have cleared which frequency formula we would be discussing in this article let us now define frequency.

Frequency Definition

The frequency of waves is defined as the number of waves produced per unit time in a given medium.
The figure given below will help you to understand the terminology used in explaining waves and its various characteristics.

sine wave


The frequency of a wave is the number of times that the particles of a medium vibrate as the wave passes through the medium. It also tells us about how many crests go through a fixed point per unit time.

Frequency Symbol

Frequency in physics is represented by the symbol $f$ or the Greek letter $\nu$.

Unit Of Frequency

The unit of frequency is a derived unit called hertz, often written as Hz and is named after Heinrich Rudolf Hertz. One Hz is one cycle per second. Here, “cycles” can be any periodic motion, such as a spring, a pendulum, anything rotating, or a wave.
Other frequency units used are

  • millihertz (mHz),
  • kilohertz (kHz),
  • megahertz (MHz),
  • gigahertz (GHz), and
  • terahertz (THz).

Frequency Formula

The Formula for frequency is given by the relation
$frequency=\frac{1}{period}$
or,
$f=\frac{1}{T}$
where,
$f$= frequency
$T$= period, the time required for one cycle

How to find the frequency from the period

Let’s look at some easy example problems now that we’ve learned about the frequency formula for a wave, which shows the relationship between frequency and time period.
Problem 1
Find the frequency of a wave where one cycle takes 0.4s using the frequency formula.
Solution
It is given in the question that
$time = 0.4 s$,
and we have to find the frequency of the wave.
We know that the frequency equation is given by the relation
$f=\frac{1}{T}$
putting the value of $T$ in the above equation we get
$f=\frac{1}{0.4}hz$
calculating it we get
$f=2.5hz$
which is the required answer
Problem 2
Find the frequency of the pendulum, whose cycles take 5 seconds to complete.
Solution
It is given in the question that
$time = 5 s$,
and we have to find the frequency of the wave.
We know that the frequency equation is given by the relation
$f=\frac{1}{T}$
putting the value of $T$ in the above equation we get
$f=\frac{1}{5}hz$
calculating it we get
$f=0.2hz$
which is the required answer

Frequently asked questions

What is $T$ in the frequency formula?

$T$ in the frequency formula is the time period of a wave. It is the time in which a particle of the medium completes one vibration to and fro about its mean position.

What is a frequency equal to in physics?

The frequency in physics is given by relation f=1/T and the time period is the time required by the vibrating particle to complete one cycle or complete one vibration to and fro about the mean position.