Sound Waves | Physics for GCSE/IGCSE - Year 11 PDF Download

Describing Sound

• Sound waves are produced by vibrating sources.
• When a sound wave contacts a solid, it can transfer vibrations to the solid. 
  • For instance, sound waves can make a drinking glass vibrate. If the glass vibrates excessively, it can shatter.

• Sound waves necessitate a medium for propagation. This implies that in the absence of molecules, as in a vacuum, sound cannot travel.

Compression & Rarefaction

• Longitudinal waves are composed of compression and rarefaction. Compression denotes a region of higher density, where molecules are closely packed, whereas rarefaction indicates a region of lower density, where molecules are more dispersed.

Sound is a longitudinal wave consisting of compressions and rarefactions - these are areas where the pressure of the air varies with the wave

• These compressions and rarefactions result in fluctuations in pressure that change over time along with the wave.
  • Consequently, sound constitutes a form of pressure wave.
• When these waves encounter a solid object, the pressure variations induce vibrations in the surface of the solid that synchronize with the sound wave.