Waves in Air, Fluids and Solids

• Waves


  Two types:
• Types of waves


  • Transverse
  • Longitudinal
• Transverse wave


  Wave for which the oscillations are perpendicular to the direction of energy transfer
• Longitudinal wave


  Wave for which the oscillations are parallel to the direction of energy transfer
• Transverse waves


  • Electromagnetic waves
  • Seismic s-waves
• Longitudinal waves


  • Sound waves
  • Seismic p-waves
• Parts of a longitudinal wave

  • Compressions
  • Rarefactions
• Wave amplitude


  The maximum displacement of a point on a wave from its undisturbed position
• Wavelength


  The distance from a point on a wave to the same position on the adjacent wave, most commonly peak to peak or trough to trough
• Wave frequency


  The number of waves that pass a given point each second
• Unit of frequency


  Hertz, Hz
• A frequency of 200Hz means 200 waves pass a given point each second
• Wave speed


  The speed at which the wave moves or at which energy is transferred through a medium
• Waves transfer energy
• Calculating wave speed


  1. Wave Speed = Frequency x Wavelength

  2. Speed (m/s), Frequency (Hz), Wavelength (m)
• Reflection


  When a wave bounces off a surface
• How sound waves travel through solids (Higher)

  The particles in the solid vibrate and transfer kinetic energy through the material
• Frequency range of human hearing (Higher)

  20 Hz - 20kHz (1kHz = 1000 Hz)
• Ultrasound waves (Higher)


  Waves which have a frequency higher than the upper limit of human hearing (20kHz)
• Uses of ultrasound waves (Higher)

  • Medical or industrial imaging
• Earthquakes cause seismic waves, which produce both P-waves and S-waves (Higher)
• Echo sounding technique (Higher)

  1. High frequency sound waves are emitted, reflected and detected

  2. Time difference between emission and detection, alongside wave speed, are used to calculate distances