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SOUND CHAPTER NO 12 PHYSICS 10TH CLASS


PHYSICS NOTES 10TH CLASS
Written by BILAL HASAN B.cs , M.cs..
NICE STUDIES ACADEMY HFD
SOUND CHAPTER NO 13
BILAL HASAN:BORROWED FEATHERS SELDOM FIT.
DEFINITIONS
Sound

Definition 
"A vibration transmitted by air or other medium in the form of alternate compressions and rarefactions of the medium is known as Sound." 

Production of Sound 
Sound is produced by a vibrating body like a drum, bell, etc, when a body vibrates. due to the to and fro motion of the drum, compressions and rarefactions are produced and transmitted or propagated in air. 

Propagation of Sound Waves 
When a body vibrates in air, it produces longitudinal waves by compressions and rarefactions. These compressions and rarefactions are traveled by the particles of the medium and transferred into the next particles. Due to this transference, sound propagates in a medium. 

Experiment 
(Diagram) 
Suspend an electric bell in a jar by its wires through a cork fixed in its mouth. Switch on the bell, we will hear the sound of the bell. Now start removing air from jar with the help of an exhaust (vacuum) pump. The sound will decrease, although the hammer is still seen striking the bell. This experiment shows that air or any other medium is necessary for the propagation of sound. 

Velocity of Sound

It is a matter of common experience that the flash of lightning is seen earlier than hearing the thunder of cloud. Similarly when a gun is fired its sound is heard a little after seeing its flash. The reason is that light is faster than sound. Due to its slow velocity sound lags behind. 
BILAL HASAN:BORROWED FEATHERS SELDOM FIT.
Experiment 
Select two stations at a distance of 8 km (or any more distance) such that there is no obstacle between them. Fire a gun at station A and note the time of sound taken for such distance. Repeat the process and note the time taken by the sound to travel from B to A. If we substitute the mean of the two times recorded and distance S (8km) in the formula V = S/t, we will get the velocity of sound. 

Factors Effecting Velocity of Sound 
The factors are given below: 
Velocity of air or any other medium.
Density of the medium.
Temperature of the medium.
Nature of the medium

BILAL HASAN:BORROWED FEATHERS SELDOM FIT.
Characteristics of Sound

The characteristic properties of sound by which we can distinguish between noise and music, shrill and grave sounds or sound of men and women are known as characteristics of sound. The properties of sound are given below: 


1.Loudness

Definition 
"Loudness is the magnitude of auditory sensation produce by sound." 
Intensity can be defined as the energy carried by the sound waves through a unit area placed perpendicular to the direction of waver per second. 

Factors Effecting Loudness of Sound 
Loudness depend on following factors: 
Area of Vibration of Body: Greater will be the surface area more will be the loudness.
Amplitude of Motion of Vibrating Object: Greater will be the amplitude, more will be the loudness.
Density of Medium: Loudness is directly proportional to the density of medium.
Motion and Direction: If source of sound is moving towards the listener loudness will be greater or if wind supports the velocity of sound the loudness will be greater.

2. Pitch

Definition 
"The sensation that a sound produces in a listener as a result of its frequency is known as Pitch." 
This is the property of sound by virtue of which we can distinguish between a shrill and grave sound. 

Factors Effecting Pitch of Sound 
Pitch depends on following factors: 
Frequency of Vibrating Body: The greater the fundamental frequency, more shrill will be the sound.
Relative Motion of Sound: If source and listener both are coming closer pitch will increase.

3. Quality or Timbre or Tone 

Definition 
"The characteristic of a musical note that is determined by the frequency present is known as Quality or Timbre or Tone of that sound." 
This is the property of sound by virtue of which it is possible to identify a sound of the same loudness and pitch but originating from different instrument. 

Factors Effecting Quality 
Quality depends upon the following factors: 
Phase of the Sound Wave.
Shape of Waves
Harmful Effects of Sound (Noise)
BILAL HASAN:BORROWED FEATHERS SELDOM FIT.
Nowadays noise is considered as a great pollution, which is very dangerous for us. Some of them are as follows: 
Continuous noise damages hearing and can result in complete deafness.
Noise has become a great cause for depression and blood pressure.
Mental system shows less efficiency due to noise.
Consequently it is harmful in all respects for living body.
BILAL HASAN:BORROWED FEATHERS SELDOM FIT.

Musical Sound

The sound producing pleasing effect on our ears are called musical sounds. 

3 comments:

Nabila said...

appreciated to share physics notes 10th class, i am really glade to view and i find it very helpful, keep it up

Asifa Khan said...

weldone

Asifa Khan said...

is intensity not a characteristic of sound?

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