Transverse & Longitudinal Waves (OCR Gateway GCSE Physics: Combined Science)

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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 wave diagram, downloadable AS & A Level Physics revision notes

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)

  • The key features of a longitudinal wave are where the points are:
    • Close together, called compressions
    • Spaced apart, called rarefactions

Longitudinal Wave Vibration Spring, downloadable IGCSE & GCSE Physics revision notes

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 wave diagram, downloadable AS & A Level Physics revision notes

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)

Wave on rope and spring, downloadable AS & A Level Physics revision notes

Waves can be shown through vibrations in ropes or springs

Comparing Transverse & Longitudinal Waves

  • The different properties of transverse and longitudinal waves are shown in the table:

Transverse Waves v Longitudinal Waves TableLongitudinal v Transverse Table, downloadable IGCSE & GCSE Physics revision notes

Examiner Tip

The key difference between transverse and longitudinal waves is the direction of the vibrations with respect to the direction of the wave itself. For transverse waves, these are perpendicular to each other, whilst for longitudinal waves, these are parallel.

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Ashika

Author: Ashika

Expertise: Physics Project Lead

Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.