What is general meaning of word Compression?
It is a region of high pressure
When a vibrating object moves forward in air as medium,
it pushes and compresses the air in front of it
creating a region of high pressure. This region is called a compression.
What is general meaning of word Rarefaction
It is a region of low pressure
When a vibrating object moves backward in air as medium,
it creates a region of low pressure. This region is called a rarefaction.
Difference between Compression and Rarefaction
|It is a region of high pressure||It is a region of low pressure|
|Air particles are closely packed together||Air particles are loosely packed|
How does Sound Waves cause Compression and Rarefaction
We know that Sound waves travel through a medium like air
When an object vibrates, it moves in to and fro motion (forward and backward)
When object moves in forward motion
It causes nearby air particles to compress
This creates a region of high pressure called compression
When object moves back in backward motion
It creates a region of low pressure
This creates a region of low pressure called rarefaction
As the object vibrates (moves backward and forward), a series of compression's and rarefaction's is created in the air.
These make the sound waves propagate through the medium
Intext Question 1 Page 163 - Explain how sound is produced by your school bell.
NCERT Question 2 -
Describe with the help of a diagram, how compressions and rarefactions are produced in air near a source of sound.