Question

give the sound chapter all notes for class 9​

Answer 1

Answer:

Wave and it’s types

�It is the periodic disturbance in a medium.

Types of Wave

There are two types of waves in general depending upon their propagation through a substance. They are as follows-

Mechanical wave

Electromagnetic wave

Mechanical Wave: It is the kind of wave which requires a medium to travel. For example: Sound Wave.

That means sound can be heard only whenever there is presence of certain substance like water, glass, air etc. It can not be heard in a vacuum no matter how loud the sound maybe.

Electromagnetic Wave: Is that which can travel through a medium as well as through vacuum. For example: Light wave.

But unlike sound, light can be seen through a substance or in vacuum. That is the reason it is referred to as electromagnetic wave.

Types of waves (depending upon the movement of particles)

We know that whenever a wave travels, the particles vibrate and they constitute the wave or we can say there periodic disturbance constitutes wave. So, depending upon the movement of particles, to produce vibrations, we have different kinds of waves as given below-

The two types of waves are as follows-

Longitudinal wave

Transverse wave

Longitudinal: It is the wave in which particles vibrate to and fro. This longitudinal wave consists of compression and rarefaction. The movement is shown in the following figure: