Transverse & Longitudinal Waves

• Transverse & Longitudinal Waves

  • Waves are repeated vibrations that transfer energy
  • Energy is transferred by parts of the wave knocking nearby parts
  • This is similar to the effect of people knocking into one another in a crowd, or a "Mexican Wave" at football matches
  • Waves can exist as one of two types:
  • Transverse
  • Longitudinal
• Transverse Waves

  • Transverse waves are defined as:Waves where the points along its length vibrate at 90 degrees to the direction of energy transfer
  • For a transverse wave:
  • The energy transfer is perpendicular to wave motion
  • They transfer energy, but not the particles of the medium
  • They can move in solids and on the surfaces of liquids but not inside liquids or gases
  • Some transverse waves (electromagnetic waves) can move in solids, liquids and gases and in a vacuum
• • The point on the wave that is:
  • The highest above the rest position is called the peak, or crest
  • The lowest below the rest position is called the trough
• Transverse waves can be seen in a rope when it is moved quickly up and down

  
• • Examples of transverse waves are:
  • Ripples on the surface of water
  • Vibrations in a guitar string
  • S-waves (a type of seismic wave)
  • Electromagnetic waves (such as radio, light, X-rays etc)
• Representing Transverse Waves

  • Transverse waves are drawn as a single continuous line, usually with a central line showing the undisturbed position
  • The curves are drawn so that they are perpendicular to the direction of energy transfer
  • These represent the peaks and troughs
• Transverse waves are represented as a continuous solid line

  
• Longitudinal Waves

  • Longitudinal waves are defined as:Waves where the points along its length vibrate parallel to the direction of energy transfer
  • For a longitudinal wave:
  • The energy transfer is in the same direction as the wave motion
  • They transfer energy, but not the particles of the medium
  • They can move in solids, liquids and gases
  • They can not move in a vacuum (since there are no particles)
• Longitudinal Waves

  • The key features of a longitudinal wave are where the points are:
  • Close together, called compressions
  • Spaced apart, called rarefactions
• Longitudinal waves can be seen in a slinky spring when it is moved quickly backwards and forwards:

  
• • Examples of longitudinal waves are:
  • Sound waves
  • P-waves (a type of seismic wave)
  • Pressure waves caused by repeated movements in a liquid or gas
• Representing Longitudinal Waves

  • Longitudinal waves are usually drawn as several lines to show that the wave is moving parallel to the direction of energy transfer
  • Drawing the lines closer together represents the compressions
  • Drawing the lines further apart represents the rarefactions
• Longitudinal waves are represented as sets of lines with rarefactions and compressions

  
• Comparing Transverse & Longitudinal Waves

  • Wave vibrations can be shown on ropes (transverse) and springs (longitudinal)

  
• Comparing Transverse & Longitudinal Waves

  • Wave vibrations can be shown on ropes (transverse) and springs (longitudinal)
  • Waves can be shown through vibrations in ropes or springs

  
• Transverse Waves v Longitudinal Waves Table: