What is a wave?

Wave is a disturbance

which travels through a medium (like liquid)

when the particles of the medium set neighbouring particles into motion.

Note -

The particles do not move, but the disturbance is carried forward from one particle to other

Mechanical Waves and Electromagnetic Waves

What are Mechanical Waves

Those waves which require a medium to propagate are called Mechanical Waves


Sound waves can travel through a medium like solid, liquid, gas

It cannot travel through a vacuum


What are Electromagnetic Waves

Those waves which do not require a medium to propagate are called Electromagnetic Waves


Light does not require a medium to propagate

It can travel even through vacuum


Difference between Sound Waves and Light Waves

Sound Light
It is a mechanical wave It is an electromagnetic wave
It requires a medium, it can not travel through vacuum It can travel even in vacuum
It is a longitudinal waves (wave which move back and forth, parallel to direction of propagation) It is a transverse waves (wave which move perpendicular to direction of propagation)


Why are sound waves called mechanical waves?

Link to Q2 Page 163

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

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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.