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CBSE Notes for Class 9 Science chapter 12. Sound: Propagation of Sound, quick revision notes for Class 9 Science chapter 12. Sound Propagation of Sound, Chapter-wise CBSE Revision Notes, CBSE Notes PDF Free Download, CBSE One Liner Notes Class 9, Half Yearly Revision Notes, CBSE Revision Notes Class 9 Science
Get CBSE Notes for Class 9 Science Chapter 12. Sound: Propagation of Sound prepared by experts as per the latest NCERT syllabus and CBSE exam pattern. These concise and easy-to-understand notes cover important definitions, formulas, diagrams, and key concepts from the chapter to help students in quick revision and effective exam preparation. Whether you are studying for school tests, board exams, or competitive exams, these notes provide a reliable study resource. Designed in simple language with point-wise explanations, they save time and enhance learning efficiency. Download free PDF notes, explore solved examples, and strengthen your understanding of [Topic Name] for scoring high marks. Perfect for Class 9 students who want clear, structured, and exam-oriented notes for CBSE Science.
Sound: When an object vibrates it produces sound.
Vibration: When an object moves fast in to and fro motion, this motion is called vibration.
Ways to produce sound:
(i) Hitting on an object.
(ii) By friction
(iii) By scratching
(iv) By rubbing
(v) By blowing or moving any object sound can be produced.
Sound in Human:
In Human being sound is produced by vibrating the vocal chords.
Propagation of Sound: The sound travels from one place to another place, this is called propagation of sound.
Medium: Sound does not propagate without any medium. It need medium to travel from one to another place. "substances like solid, liquid or gas provides medium to sound for propagation, such substances are called mediums."
Definition of medium: The matter or substance through which sound is transmitted is called a medium.
Medium of Sound for Propagation:
There are three medium by which sound propagates.
(i) Solid like metalic rod, glass, wood etc.
(ii) Liquid like water, oil and drinks etc.
(iii) Gas like air, and other gases.
How does the sound propagates?
When an object vibrates, it sets the particles of the medium around it vibrating. A particle of the medium in contact with the vibrating
object is first displaced from its equilibrium position. It then exerts a force on the adjacent particle. As a result of which the adjacent particle gets displaced from its position of rest. After displacing the adjacent particle the first particle comes back to its original position. This process continues in the medium till the sound reaches our ear.
Compression: When a vibrating object moves forward, it pushes and compresses the air in front of it creating a region of high pressure. This region is called a compression(C).
Rarefaction: When the vibrating object moves backwards, it creates a region of low pressure called rarefaction (R).
Differences between compression and rarefaction:
Compression:
(i) It creates when object moves forward.
(ii) Compression is the region of high pressure.
Rarefaction:
(i) It creates when objects moves backward.
(ii) Rarefaction is the region of low pressure.
Propagation of density variations or pressure variations:
Pressure is related to the number of particles of a medium in a given volume. More density of the particles in the medium gives more pressure and vice versa. Thus, propagation of sound can be visualised as propagation of density variations or pressure variations in the medium.
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Ace your exams with CBSE Notes for Class 9 Science chapter 12. Sound: Propagation of Sound. These notes provide a clear explanation of important concepts, formulas, diagrams, and solved examples from the NCERT syllabus. Specially designed for Class 9 students, the notes are structured in a simple, point-wise manner to make revision quick and effective. Whether you are preparing for school tests, board exams, or competitive exams, these Science notes will boost your confidence and save valuable study time. You can also download Science class 9 chapter 12. Sound free PDF notes for offline learning. With easy-to-grasp language, exam tips, and well-organized content, these CBSE Science notes on chapter 12. Sound – Propagation of Sound are the perfect study companion for scoring high marks and mastering the subject.
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