{"id":15842,"date":"2023-06-22T11:21:52","date_gmt":"2023-06-22T05:51:52","guid":{"rendered":"https:\/\/apboardsolutions.in\/?p=15842"},"modified":"2023-06-23T17:13:01","modified_gmt":"2023-06-23T11:43:01","slug":"ap-board-9th-class-physical-science-notes-chapter-11","status":"publish","type":"post","link":"https:\/\/apboardsolutions.in\/ap-board-9th-class-physical-science-notes-chapter-11\/","title":{"rendered":"AP Board 9th Class Physical Science Notes Chapter 11 Sound"},"content":{"rendered":"

Students can go through AP State Board 9th Class Physical Science Notes<\/a> Chapter 11 Sound to understand and remember the concept easily.<\/p>\n

AP State Board Syllabus 9th Class Physical Science Notes Chapter 11 Sound<\/h2>\n

\u2192 Sound is produced by a vibrating body.<\/p>\n

\u2192 Sound is transmitted through a medium and received by our ears.<\/p>\n

\u2192 A sound is a form of energy.<\/p>\n

\u2192 Sound travels through disturbances in the form of waves.<\/p>\n

\u2192 The matter or the substance through which sound is transmitted is called the medium. If the particles of the medium vibrate along the direction of the wave, then the wave is called a longitudinal wave. Sound waves are longitudinal.<\/p>\n

\u2192 Longitudinal waves consist of compressions and rarefactions.<\/p>\n

\u2192 The region of the high density of particles in the medium during propagation of sound is called compression and low-density regions are called rarefaction.<\/p>\n

\u2192 The distance between two consecutive compressions or two successive rarefactions is called the wavelength of a sound wave.<\/p>\n

\u2192 If the particles of the medium vibrate perpendicular to the direction of the wave, then the wave is called a transverse wave.<\/p>\n

\u2192 The maximum variation in density or pressure from the mean value is called amplitude. The number of oscillations of the density of the medium at a place per unit time is called the frequency of the sound wave.<\/p>\n

\u2192 The time taken to complete one oscillation of the density of the medium is called the time period of the sound wave.<\/p>\n

\u2192 Frequency and time period are related as T = 1\/u or o = 1\/T<\/p>\n

\u2192 The distance by which a point on the wave, such as a compression or rarefaction travel in unit time is called the speed of the sound wave.<\/p>\n

\u2192 The relation between the speed of a sound wave, wavelength, and frequency is v = uA.<\/p>\n

\u2192 The sounds which produce pleasing effects on the ear are called musical sounds, while the sounds which produce unpleasant effects are called noises.<\/p>\n

\u2192 The characteristics by which one can distinguish a musical note from another are pitch, loudness, and quality.<\/p>\n

\u2192 Pitch is a characteristic of sound which distinguishes between a shrill sound and a deep, low sound.<\/p>\n

\u2192 The loudness of sound is defined as the degree of sensation produced in the ear, measured in decibels.<\/p>\n

\u2192 The quality of sound is the characteristic that enables us to distinguish between musical notes emitted by different musical instruments.<\/p>\n

\u2192 Sound reflects as light reflects.<\/p>\n

\u2192 A reflection of sound, arriving at the listener in more than 0.1 s after the direct sound is called an echo.<\/p>\n

\u2192 A reflection of sound, arriving at the listener in less than 0.1 s after the direct sound is called reverberation.<\/p>\n

\u2192 The human ears are able to hear sound in a frequency range of about 20 Hz to 20 kHz. Sounds of frequency less than 20 Hz are known as infrasonic sounds.<\/p>\n

\u2192 Sounds of frequency higher than 20 kHz are known as ultrasonic sounds.<\/p>\n

\u2192 Ultrasonic waves are used in drilling holes or making cuts of different shapes, cleaning, detection of defects in metals, in the medical field to imaging of organs, surgeries, etc.<\/p>\n

\u2192 SONAR stands for Sonographic Navigation and Ranging.<\/p>\n

\u2192 SONAR is equipment or a system for finding objects underwater using sound waves.
\n\u2192 Mechanical energy: Energy produced by mechanical means like pushing, pulling, beating, vibrating, etc. is known as mechanical energy.<\/p>\n

\u2192 Tuning fork: A tuning fork is an acoustic resonator. It is a steel bar, bent in U-shape, with a handle at the bend. It resonates at a specific constant pitch when set into vibration by a string with a rubber hammer.<\/p>\n

\u2192 Longitudinal wave: If the particles of the medium vibrate along the direction of the wave, then the wave is called a longitudinal wave.<\/p>\n

\u2192 Transverse wave: If the particles of the medium vibrate perpendicular to the direction of the wave, then the wave \u00a1s called a transverse wave.<\/p>\n

\u2192 Compression: Compression is the region where density, as well as the pressure of particles in the medium, is high.<\/p>\n

\u2192 Rarefaction: Rarefaction is the region where density, as well as the pressure of particles in the medium, is low.<\/p>\n

\u2192 Crest: Crest is a point where the amplitude of a wave is maximum in a transverse wave.<\/p>\n

\u2192 Trough: A trough is a point where the amplitude of a wave is minimum in a transverse wave.<\/p>\n

\u2192 Pressure: Pressure is force per unit area applied in a direction .perpendicular to the surface of an object. The SI unit of pressure is the newton per square meter, which is called the pascal (Pa) after the seventeenth-century philosopher and scientist Blaise Pascal.<\/p>\n

\u2192 Wavelength: The distance between two consecutive compressions or two consecutive rarefactions is called the wavelength of a sound wave.<\/p>\n

\u2192 Amplitude: The maximum variation in density or pressure from the mean value is called amplitude.
\n(or)
\nThe maximum disturbance of the particles of a medium from their mean position is called amplitude.<\/p>\n

\u2192 Frequency: The number of oscillations of the density of the medium at a place per unit time is called frequency.<\/p>\n

\u2192 Pitch: Pitch is a characteristic of sound which distinguishes between a shrill sound and a deep, low sound.<\/p>\n

\u2192 Loudness: Loudness of sound is defined as the degree of sensation produced in the ear.<\/p>\n

\u2192 Quality of sound: The quality of sound is the characteristic that enables us to distinguish between musical notes emitted by different musical instruments.<\/p>\n

\u2192 Echo: A reflection of sound, arriving at the listener in more than 0.1 s after the direct sound is called an echo.<\/p>\n

\u2192 Reverberation: A reflection of sound, arriving at the listener in less than 0.1 s, after the direct sound is called reverberation.<\/p>\n

\u2192 Infrasonic: Sound of frequency less than 20Hz is known as infrasonic sound.<\/p>\n

\u2192 Sonic: Of or relating to audible sound. e.g: a sonic wave.<\/p>\n

\u2192 Ultrasonic: Sound of frequency greater than 20 kHz is known as ultrasonic sound.<\/p>\n

\u2192 SONAR: SONAR stands for Sonographic Navigation And Ranging. It is equipment or a system for finding objects underwater using sound waves.
\n\"AP
\n\u2192 Heinrich Rudolf Hertz:
\nHeinrich Rudolf Hertz was born on 22 February 1857 in Hamburg, Germany, and educated at the University of Berlin. He was the first to conclusively prove the existence of electromagnetic waves. He laid the foundation for the future development of radio, telephone, telegraph, and even television. He also discovered the photoelectric effect which was later explained by Albert Einstein. The SI unit of frequency was named Hertz in his honor.<\/p>\n","protected":false},"excerpt":{"rendered":"

Students can go through AP State Board 9th Class Physical Science Notes Chapter 11 Sound to understand and remember the concept easily. AP State Board Syllabus 9th Class Physical Science Notes Chapter 11 Sound \u2192 Sound is produced by a vibrating body. \u2192 Sound is transmitted through a medium and received by our ears. \u2192 … Read more<\/a><\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"spay_email":""},"categories":[8],"tags":[],"jetpack_featured_media_url":"","_links":{"self":[{"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/posts\/15842"}],"collection":[{"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/comments?post=15842"}],"version-history":[{"count":1,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/posts\/15842\/revisions"}],"predecessor-version":[{"id":41419,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/posts\/15842\/revisions\/41419"}],"wp:attachment":[{"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/media?parent=15842"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/categories?post=15842"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/apboardsolutions.in\/wp-json\/wp\/v2\/tags?post=15842"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}