sound class 9th notes
sound class 9th notes
sound class 9th notes cbse, science class 9 notes all chapter, sound class 9th notes explained in full detailed topic wise full explanation, class 9 science notes chapter sound.
Here we covered the whole topic of sound class 9 cbse, like what is sound, characteristic of sound, types of material medium need to travel sound, types of wave, wave motion, Reflection of sound etc.
Here we covered the whole topic of sound class 9 cbse, like what is sound, characteristic of sound, types of material medium need to travel sound, types of wave, wave motion, Reflection of sound etc.
What is sound?
- sound is a form of energy.
- All vibrating body produced sound.
- sound is that form of energy which makes us here.
Characteristic of sound
Sound needs a material medium to travels.
Medium:- The substance through which sound travels is called a medium.
Note:- Hence we can say sound can travels through a medium solid, liquid and gasses, but it cannot travels through vaccum.
Sound can travels through solid
If a child speaks into one tin he can be here by another child who puts his ear to the other tin. It means that sound can travels through solid.
Sound can travels through liquid
If we fill a balloon with water and hold it near our ear then hit by a finger in lower side of the balloon with some force then we observe that some is hearing, so we conclude by this experiment when we git balloon then water molecules vibrate up and down rapidly and we here sound.
it means that sound can travels through water.
Sound can travels through gasses
When our parents talk to each other then we here sound because of disturbance of the particles of the air. we know that air is a gas so, sound can travels through gas.
it is the same reason for telephone bell when it ring.
Sound can't travels through vaccum
- A material medium ( like air ) is necessary for propagation of sound.
- In outer space there is no air present so we know that for propagation of sound a material medium must be able to carry sound waves from one place to another place but there is no material medium is present so sound cannot travels through vaccum. also sound cannot be hered in outer space or even in any place where air is not present then sound cannot travels on there. for propagation of sound there is very - very necessary a material medium like air.
- We cannot be talked on the moon like on the earth so space man can talk by radio wave. radio wave can travels through vaccum or in empty space because it an electromagnetic wave. we discuss about electromagnetic waves in latter topic.
Sound travels in the form of waves
sound travels in the form of wave or even light also travels in the form of waves. we all know that sound is a form of energy so wave carry energy. wave is a vibrating disturbance in the air which carry energy from one place to another place.
Sound is a disturbance in the the medium and it is also a form of energy so sound wave carry energy from one point to another point.
If we through a stone into a pond then we saw a concentric circle in the pond produced that is called the wave of sound namely transverse wave.
when a water waves passes over the surface of the water in a pond, there is no actual movement of water from the center to the side of the pond only the water molecules vibrates up and down about their fixed positions due to this reason water molecules appears to be moving to us.
- A periodic disturbance produce in a material medium due to the vibrating motion of the particles of medium is called wave.
Wave motion:-
It is the movement of disturbance produce to in one part of a medium to another involving the transfer of energy but not the transfer of matter, is called wave motion.
example:- Formation of ripples on the water surface. and propagation of sound wave through air or any other material medium.
Characteristic of wave motion
- In wave motion the particles of the medium vibrate about their mean position. the particls of the medium do not move from one place to another place.
- A wave motion travels by the same speed in all direction from the sound producing object in any medium.
- In wave motion medium do not moves but the disturbance travels through the medium.
- During a wave motion energy is transfer from one point of the medium to the another there is no transfer of matter through the medium.