7. Waves

• Waves 


  Repeated vibrations that transfer energy
• 2 Types of Waves 


  Transverse

  Longitudinal
• Transverse Waves 


  Waves where the point along its length vibrate at 90 degrees to the direction of energy transfer
• How does a Transverse Wave work?


  • the energy transfer is perpendicular to wave motion
  • they transfer energy, but not the particles of the medium
  • can move in solids and on surfaces of liquids but not inside liquids or gases
  • some transverse waves can move in solids, liquids, gases and in a vacuum
• Highest above the rest position called PEAK or CREST

  Lowest below rest position called TROUGH
• Transverse Wave

  
• Examples of Transverse Waves :


  Ripples on the surface of water

  Vibrations in a guitar string

  S-waves

  Electromagnetic waves - light, radio, x-rays
• Representing Transverse Waves

  
• Longitudinal Waves 


  Waves where the points along its length vibrate parallel to the direction of energy transfer
• Features of a Longitudinal Wave


  • the energy transfer is in the same direction as the wave motion
  • transfers energy but not the particles of the medium
  • moves in solids, liquids and gases
  • CANNOT move in vacuums (there are no particles)
• Longitudinal Wave 


  Points are close together, called COMPRESSIONS

  Points are spaced apart, called RAREFACTIONS
• Longitudinal Waves

  
• Examples of Longitudinal Waves 


  Sound waves

  P-waves

  Pressure waves caused by repeated movements in a liquid or gas
• Representing Longitudinal Waves

  
• Transverse vs Longitudinal Waves

  
• Wavefronts 


  Waves are viewed from above
• Transverse Waves - Wavefront 


  One line represents either a PEAK or TROUGH
• Longitudinal Wave - Wavefront 


  One line represents either a COMPRESSION or RAREFACTION
• Wavefronts Representation


  The arrows shows the direction the wave is moving also called a 'ray'

  Space in between the lines represents the wavelength

  Lines close together - wave with short wavelength

  Lines far apart - wave with long wavelength