{"id":7860,"date":"2026-07-07T13:03:16","date_gmt":"2026-07-07T07:33:16","guid":{"rendered":"https:\/\/enlightify.org\/?p=7860"},"modified":"2026-07-07T13:19:40","modified_gmt":"2026-07-07T07:49:40","slug":"amplitude-and-intensity-of-sound-waves","status":"publish","type":"post","link":"https:\/\/enlightify.org\/hi\/amplitude-and-intensity-of-sound-waves\/","title":{"rendered":"Amplitude and Intensity of Sound Waves"},"content":{"rendered":"
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Amplitude and Intensity of Sound Waves<\/h1>\n\n

Introduction<\/h2>\n\n

\nSound waves travel through a medium as alternate compressions and rarefactions. During this propagation, the density of the medium changes periodically.\n<\/p>\n\n

\nTwo important characteristics of a sound wave are amplitude<\/strong> and intensity<\/strong>. Amplitude tells us how large the density variation is, while intensity tells us how much sound energy passes through a given area in a given time.\n<\/p>\n\n

Amplitude of a Sound Wave<\/h2>\n\n

\nThe amplitude of a sound wave is the maximum change in the density of the medium in a compression or rarefaction compared to the average density.\n<\/p>\n\n

\nIn simple words, amplitude tells us how much the density of the medium changes from its normal value.\n<\/p>\n\n

\nAmplitude = Maximum change in density from average density<\/strong>\n<\/p>\n\n

Average Density<\/h2>\n\n

\nAverage density is the normal density of the medium when there is no sound disturbance.\n<\/p>\n\n

\nWhen a sound wave passes through a medium, the density of the medium increases above average density in compressions and decreases below average density in rarefactions.\n<\/p>\n\n

Low Amplitude and High Amplitude<\/h2>\n\n

\nA sound wave may have low amplitude or high amplitude.\n<\/p>\n\n

    \n
  • \nA low amplitude<\/strong> sound wave has a small change in density.\n<\/li>\n\n
  • \nA high amplitude<\/strong> sound wave has a large change in density.\n<\/li>\n<\/ul>\n\n

    \nGreater amplitude means greater disturbance in the particles of the medium.\n<\/p>\n\n

    Figure<\/h2>\n\n
    \n\n\n \n \n Low Amplitude and High Amplitude Sound Waves\n <\/text>\n\n \n \n Low Amplitude\n <\/text>\n\n \n \n\n \n\n \n\n \n\n \n \n\n Average density<\/text>\n\n \n \n\n \n \n\n \n\n \n\n Small amplitude<\/text>\n\n \n Distance<\/text>\n Density<\/text>\n\n \n \n High Amplitude\n <\/text>\n\n \n \n\n \n\n \n\n \n\n \n \n\n Average density<\/text>\n\n \n \n\n \n \n\n \n\n \n\n Large amplitude<\/text>\n\n \n Distance<\/text>\n Density<\/text>\n\n \n \n\n \n Amplitude and Energy\n <\/text>\n\n \n \n\n \n\n Small amplitude<\/text>\n Less energy<\/text>\n\n \n \n\n \n\n \n\n Large amplitude<\/text>\n More energy<\/text>\n\n \n \n\n \n Larger amplitude means the sound wave carries more energy.\n <\/text>\n\n<\/svg>\n<\/div>\n\n

    Explanation of the Figure<\/h2>\n\n

    \nThe figure compares low amplitude and high amplitude sound waves. In both graphs, the dashed line represents the average density of the medium.\n<\/p>\n\n

    \nIn the low amplitude wave, the density changes only slightly above and below the average density. In the high amplitude wave, the density changes more from the average density.\n<\/p>\n\n

    \nA wave with larger amplitude carries more energy than a wave with smaller amplitude.\n<\/p>\n\n

    Amplitude and Energy<\/h2>\n\n

    \nAmplitude and energy of a sound wave are closely related.\n<\/p>\n\n

    \nA sound wave with larger amplitude carries more energy. A sound wave with smaller amplitude carries less energy.\n<\/p>\n\n

    \nFor example, when a metal plate is struck gently, it produces a sound of smaller amplitude. When the same plate is struck harder, more energy is transferred to the surrounding medium and a sound of larger amplitude is produced.\n<\/p>\n\n

    \nLarger amplitude \u2192 More energy<\/strong>\n<\/p>\n\n

    \nSmaller amplitude \u2192 Less energy<\/strong>\n<\/p>\n\n

    Activity Example<\/h2>\n\n

    \nIn the activity with grains placed on a stretched sheet, a loud sound makes the sheet vibrate and causes the grains to move or jump.\n<\/p>\n\n

    \nIf the sound source is struck harder, more energy is transferred to the particles of air. This makes the sheet vibrate with greater displacement, and the grains jump higher.\n<\/p>\n\n

    \nThis shows that a sound wave with larger amplitude carries more energy.\n<\/p>\n\n

    Intensity of Sound<\/h2>\n\n

    \nThe amount of sound energy passing through a unit area perpendicular to the direction of propagation of sound wave in one second is called the intensity of sound<\/strong>.\n<\/p>\n\n

    \nIntensity = Sound energy passing through unit area per unit time<\/strong>\n<\/p>\n\n

    \nIntensity is a measurable physical quantity. It depends on the amount of energy carried by the sound wave and the area over which the sound energy spreads.\n<\/p>\n\n

    Simple Formula for Intensity<\/h2>\n\n

    \nIf sound energy \\(E\\)<\/strong> passes through area \\(A\\)<\/strong> in time \\(t\\)<\/strong>, then intensity can be written as:\n<\/p>\n\n

    \n\\(I=\\frac{E}{A\\,t}\\)<\/strong>\n<\/p>\n\n

    where,<\/p>\n\n

      \n
    • \n\\(I\\)<\/strong> = Intensity of sound\n<\/li>\n\n
    • \n\\(E\\)<\/strong> = Sound energy\n<\/li>\n\n
    • \n\\(A\\)<\/strong> = Area\n<\/li>\n\n
    • \n\\(t\\)<\/strong> = Time\n<\/li>\n<\/ul>\n\n

      Intensity and Distance from Source<\/h2>\n\n

      \nAs a sound wave travels away from its source, it spreads over a larger area.\n<\/p>\n\n

      \nSince the same sound energy spreads over a larger area, the intensity of sound decreases with distance from the source.\n<\/p>\n\n

      \nDistance from source increases \u2192 Intensity decreases<\/strong>\n<\/p>\n\n

      Figure: Intensity Decreases with Distance<\/h2>\n\n
      \n\n\n \n \n Intensity Decreases with Distance\n <\/text>\n\n \n \n\n Source<\/text>\n\n \n \n\n \n\n \n\n \n\n \n Near source<\/text>\n High intensity<\/text>\n\n Far from source<\/text>\n Low intensity<\/text>\n\n \n \n\n \n\n \n Sound energy spreads over larger area\n <\/text>\n\n \n \n\n \n Intensity becomes smaller as distance from source increases.\n <\/text>\n\n<\/svg>\n<\/div>\n\n

      Explanation of the Figure<\/h2>\n\n

      \nThe figure shows sound spreading from a source. Near the source, sound energy is concentrated in a smaller area, so the intensity is higher.\n<\/p>\n\n

      \nFarther from the source, the same energy spreads over a larger area. Therefore, the intensity becomes lower.\n<\/p>\n\n

      Amplitude and Loudness<\/h2>\n\n

      \nHumans usually perceive a sound wave of larger amplitude as a louder sound and a sound wave of smaller amplitude as a softer sound.\n<\/p>\n\n

      \nHowever, loudness is related to our hearing experience, while intensity is a measurable physical quantity.\n<\/p>\n\n

      Difference Between Amplitude and Intensity<\/h2>\n\n\n\n\n\n\n\n\n
      Amplitude<\/th>\nIntensity<\/th>\n<\/tr>\n\n
      It is the maximum change in density from average density.<\/td>\nIt is the sound energy passing through unit area per unit time.<\/td>\n<\/tr>\n\n
      It describes the size of disturbance in the medium.<\/td>\nIt describes the amount of sound energy received per unit area per unit time.<\/td>\n<\/tr>\n\n
      Larger amplitude means more energy carried by the wave.<\/td>\nGreater intensity means more sound energy is received.<\/td>\n<\/tr>\n\n
      It is shown by the height of the wave from the average density line.<\/td>\nIt decreases as sound spreads over larger area.<\/td>\n<\/tr>\n\n<\/table>\n\n

      Examples from Daily Life<\/h2>\n\n
        \n
      • \nA softly struck drum produces a sound of smaller amplitude.\n<\/li>\n\n
      • \nA strongly beaten drum produces a sound of larger amplitude.\n<\/li>\n\n
      • \nSound is louder near a speaker because intensity is greater near the source.\n<\/li>\n\n
      • \nSound becomes softer as we move away from the speaker because intensity decreases.\n<\/li>\n\n
      • \nA loud sound can make light objects vibrate because it carries more energy.\n<\/li>\n<\/ul>\n\n

        Important Terms<\/h2>\n\n

        1. Amplitude<\/h3>\n\n

        \nThe maximum change in density of the medium from the average density in a compression or rarefaction.\n<\/p>\n\n

        2. Average Density<\/h3>\n\n

        \nThe normal density of the medium when there is no sound disturbance.\n<\/p>\n\n

        3. Intensity of Sound<\/h3>\n\n

        \nThe amount of sound energy passing through unit area perpendicular to the direction of sound propagation in unit time.\n<\/p>\n\n

        4. Loudness<\/h3>\n\n

        \nThe sensation by which we judge a sound as loud or soft.\n<\/p>\n\n

        5. Sound Energy<\/h3>\n\n

        \nThe energy carried by sound waves through a medium.\n<\/p>\n\n

        Important Points<\/h2>\n\n
          \n
        • \nAmplitude is an important characteristic of a sound wave.\n<\/li>\n\n
        • \nThe amplitude of a sound wave is the maximum change in density from average density.\n<\/li>\n\n
        • \nA larger change in density means a larger amplitude.\n<\/li>\n\n
        • \nA wave with larger amplitude carries more energy.\n<\/li>\n\n
        • \nA wave with smaller amplitude carries less energy.\n<\/li>\n\n
        • \nIntensity is the amount of sound energy passing through unit area in unit time.\n<\/li>\n\n
        • \nIntensity is a measurable physical quantity.\n<\/li>\n\n
        • \nIntensity decreases as distance from the source increases.\n<\/li>\n\n
        • \nSound spreads over a larger area as it moves away from the source.\n<\/li>\n\n
        • \nHumans generally hear larger amplitude sounds as louder sounds.\n<\/li>\n<\/ul>\n\n

          Conclusion<\/h2>\n\n

          \nAmplitude and intensity are important characteristics of sound waves. Amplitude is the maximum change in density of the medium from its average density. A larger amplitude means that the sound wave carries more energy. Intensity is the amount of sound energy passing through unit area per unit time. As sound travels away from its source, it spreads over a larger area, so its intensity decreases. Thus, amplitude is related to the energy carried by the wave, while intensity describes how much sound energy passes through a given area in a given time.\n<\/p>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>","protected":false},"excerpt":{"rendered":"

          Amplitude and Intensity of Sound Waves Introduction Sound waves travel through a medium as alternate compressions and rarefactions. During this propagation, the density of the medium changes periodically. Two important characteristics of a sound wave are amplitude and intensity. Amplitude tells us how large the density variation is, while intensity tells us how much sound […]<\/p>\n","protected":false},"author":9,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[98],"tags":[],"class_list":["post-7860","post","type-post","status-publish","format-standard","hentry","category-physics"],"_links":{"self":[{"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/posts\/7860","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/comments?post=7860"}],"version-history":[{"count":4,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/posts\/7860\/revisions"}],"predecessor-version":[{"id":7867,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/posts\/7860\/revisions\/7867"}],"wp:attachment":[{"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/media?parent=7860"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/categories?post=7860"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/enlightify.org\/hi\/wp-json\/wp\/v2\/tags?post=7860"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}