What is Frequency?
The number of times an event occurs in a given period of time is called frequency.
For example, if one bus arrives every five minutes at a particular bus stop, then we can say that the frequency of buses on this route is 1 bus per 5 minutes.
In terms of an oscillatory motion, frequency is the number of oscillations per second of an object.
The motion of a pendulum is an example of oscillatory motion. It rests at its mean position. When set into motion, it moves from one extreme to another. It completes one oscillation when it moves from its mean position to right extreme then crosses the mean position and moves to its left extreme and then finally back to its mean position.
The number of oscillations completed by it in one second will be its frequency.
It is measured in hertz and the symbol used for hertz is Hz. One hertz is defined as one oscillation per second.
What is Pitch?
It is a perpetual property of sound which helps us to identify whether the sounds are high or low. It directly depends on the frequency of the sound. That is, high-frequency sounds have a high pitch and low-frequency sounds have a low pitch.
There is no relation between the pitch and loudness level of a sound. For instance, the sound of chalk screeching on a blackboard has a high pitch but it is not so loud compared to the sound of a drum which has a lower pitch but comparatively higher loudness level.
What is Amplitude?
Amplitude is defined as the maximum displacement of an object from its mean position. In case of an oscillating pendulum, its amplitude will be the maximum displacement of the pendulum from its mean position.
What is Loudness?
It is a property of sound that depends directly on the amplitude. More the amplitude of the vibration more will be its loudness level.
In fact, the loudness of sound is proportional to the square of the amplitude. If the amplitude becomes twice, the loudness increases by a factor of four. If the amplitude is three times the original, loudness will increase by a factor of nine.
What is Time Period?
Time taken by an object to complete one oscillation is called its Time period. If an object completes one oscillation in one millisecond, its time period is one millisecond. If it completes one oscillation in ten milliseconds, its time period is ten milliseconds.
Summary
| Frequency | The number of times an event occur in a given period of time |
| Pitch | A perpetual property of sound that helps identify whether sound is high or low |
| Amplitude | The maximum displacement of an object from its mean position |
| Loudness | Property of sound that depends directly on the amplitude |
| Time Period | Time taken by an object to complete one oscillation |