Fundamental Physics/Sound

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Sound[edit]

Sound comes from many sources . For example, sound comes from human talk , sound from dog barks, bird chirp , Music's instruments like guitar, drum ..., sound from collision of 2 objects like sound of 2 cars collide with each other

Sound chracteristics[edit]

  • Sound does not exist in vacuum (air free medium) . Experient shows that bell doen't sound when place in a jar without air
  • Sound changes when it travels through matter's material medium (Solid,Liquid,Gas) according to medium's temperature and pressure
In air , 333m/s . In air, sound travels as longitudinal wave of thick and thin air columns called rare fraction and rare compressioned at a speed of 343 m/s
In liquid , 333m/s
In gas , 333m/s
  • Sound has a sound's spectrum
Audible sound . Sound audible to human's ears in the frequency range 20Hz - 20KHz . f = 20Hz - 20KHz
Ultra sound . Sound above 20KHz . f > 20KHz
Sonar sound Sound below 20Hz . f < 20KHz


  • When travelling wave hits blocking object will exhibit the following Wave effects
Sound effects Definition Illustration
Reflection Sóng bị vật cản trên đưong di chuyển phản hồi trở về Ray Diagram 2.PNG
Refraction Sóng bị lệch khi di chuyển qua vật cản Ray Diagram.PNG
Diffraction Sóng di chuyển qua khe hẹp tạo Sóng Khuếch đại Two-Slit Diffraction.png
Interference Sóng cùng chiều hay khác chiều di chuyển hướng vào nhau giao thoa với nhau cho ra Nhiểu Sóng Cộng hay Nhiểu Sóng Trừ Two-Slit Diffraction.png


Sound applications[edit]

Reference[edit]