Difference Between Frequency and Relative Frequency

Frequency vs Relative Frequency

Frequency and relative frequency are two concepts that are discussed in physics and related subjects. Frequency is the number of occurrences per unit type. Relative frequency is the frequency of an event with respect to another. Both of these concepts are fairly important in the understanding of waves and vibrations and various other fields in physics and statistics. In this article, we are going to discuss what frequency and relative frequency are, their definitions, applications, similarities, and finally the difference between frequency and relative frequency.


Frequency is a concept discussed in periodic motions of objects. To understand the concept of frequency, a proper understanding of periodic motions is required. A periodic motion can be considered as any motion that repeats itself in a fixed time period. A planet revolving around the sun is a periodic motion. A satellite orbiting around the earth is a periodic motion too, and even the motion of a balance ball set is a periodic motion. Most of the periodic motions we encounter are circular, linear or semi-circular.

A periodic motion has a frequency, which means how “frequent” the event recurs. For simplicity, we take frequency as the occurrences per second. Periodic motions can either be uniform or non-uniform. A uniform periodic motion can have a uniform angular velocity. Functions such as amplitude modulation can have double periods. They are periodic functions encapsulated in other periodic functions. The inverse of the frequency of the periodic motion gives the time for a period.

Simple harmonic motions and damped harmonic motions are also periodic motions. Thereby the frequency of a periodic motion can also be obtained using the time difference between two similar occurrences. The frequency of a simple pendulum only depends on the length of the pendulum and the gravitational acceleration for small oscillations.

Frequency is also discussed in statistics. The absolute frequency is the number of times an event is repeated over a given time or over a unit time.

Relative Frequency

Relative frequency is the frequency of an event with respect to another event. Relative frequency is a concept discussed under statistics. Statistically, relative frequency is the number of occurrences of event 1 when total events are normalized.

The statistical process has absolute frequencies and relative frequencies. When a set of absolute frequencies is normalized, each value corresponding to the original absolute frequency value is the relative frequency of the system.


What is the difference between Frequency and Relative Frequency?

• Frequency is a topic discussed in statistic and physics, whereas relative frequency is discussed only in statistics.

• The summation of frequencies can take any value for a given statistical problem, but the summation of relative frequencies is equal to 1.

• Relative frequency can take any value, but relative frequency can take values only between 0 and 1.