We have already learnt that Sound waves cause Compression and Rarefaction

In compression

Particles of medium (air particles) are tightly packed, hence there is more density and more pressure

In refraction,

Particles of medium (air particles) are loosely packed, hence they have less density and less pressure

 

Plotting them on Graph

We get peaks and trough as follows

wavelength-of-sound-wave.jpg

Wavelength of Sound Wave

 

 

Note

The peak represents region of highest compression. It is called the crest.

The valley represents region of rarefaction. It is called the trough.

What is Wavelength of Sound Wave

The distance between any two consecutive compressions or rarefactions is called wavelength.

SI unit of wavelength is metre (m)

It is denoted by lambda. (λ)

Explanation

Wavelength is the distance between

2 consecutive compressions (2 Crests)

or

2 consecutive Rarefactions (2 Troughs)

wavelength-of-a-sound-wave---teachoo.png

 

It is denoted by lamda (λ)

Its SI Unit is meter

  1. Class 9
  2. Chapter 12 Class 9 - Sound

About the Author

CA Maninder Singh's photo - Founder at Teachoo
CA Maninder Singh
CA Maninder Singh is a Chartered Accountant for the past 11 years and a teacher from the past 11 years. He teaches Science, Accounts and English at Teachoo