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Tuesday, March 1, 2011

Physics Form 5: Chapter 1 - Refraction of Sound Wave

  • During day, the layers of air near the ground is warmer than the layers of air higher up.
  • Air layer near the ground is less dense.
  • Therefore, sound wave is bent toward the normal.

  •  At night, the layers of air near the ground is cool faster than the layers of air higher up.
  •  Air layer near the ground is denser.
  • Sound travels faster in warm air than in cool air resulting increasing of wavelength.
  • When the angle of incidence is larger than the critical angle, total internal reflection occurs.
  • Therefore, the path of the sound curves reflects downwards and you can hear the sound easily at night.

Click on the diagram below to play! 

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