Fundamental Physics/Sound

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  • Sound comes from sound sources
Human's voice . Sound comes from human talk
Animal's sound . Dog barks, bird chirp ...
Music's instruments . Sound from guitar, drum ... .
  • From collision of 2 objects
Sound of 2 cars collide

Sound chracteristics[edit]

Travelling Medium[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 speed[edit]

  • 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 Spectrum[edit]

  • 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

Sound effects[edit]

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