Class 9 Science Sound

Chapter 12 of the class 9 science textbook typically covers the topic of sound. Some of the main concepts that may be covered in this chapter include:

The nature of sound and how it travels as a wave
The properties of sound waves, such as frequency, amplitude, and wavelength
The speed of sound in different mediums and how it is affected by temperature and pressure
The human ear and how it perceives sound
The production, propagation, and reception of sound
Acoustics and architectural acoustics
Ultrasound and its uses in medicine and industry
Noise pollution and its effects on health and the environment

Some of the key terms that may be discussed in this chapter include:

Sound wave
Noise pollution
This is just a general overview of what might be covered in a class 9 science chapter 12 on sound, and the specific content may vary depending on the textbook and curriculum being used.


  • The sensation felt by our ears is called Sound.
  • A sound is a form of energy that makes us hear.
  • Sound travels in form of waves.

Characteristics of Sound waves

The characteristics of sound waves are:- Wavelength, Frequency, Amplitude, Time period, and Velocity.

Wavelength of Sound waves

The distance between two consecutive identical points on a wave is known as the Wavelength of that soundwave. For example, the distance between two consecutive peaks or two consecutive troughs of a wave is one wavelength. It is a measure of how long the wave is. The wavelength is often represented by the Greek letter lambda (λ) and is measured in units of distance such as meters (m) or centimeters (cm).

Frequency of Sound

Amplitude of Sound

Time period

Velocity of Sound

Class 9 science Chapter: 11:- Work and Energy

Class 9 science Chapter: 13:- Why do we fall ill?

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