Graphical Representations of Transverse & Longitudinal Waves (OCR A Level Physics)

Revision Note

Test yourself
Katie M

Author

Katie M

Last updated

Graphical Representations of Transverse & Longitudinal Waves

  • Transverse and longitudinal waves can be represented graphically

Transverse Waves

  • Transverse waves show areas of crests (peaks) and troughs

Transverse wave diagram, downloadable AS & A Level Physics revision notes

Diagram of a transverse wave

  • The peaks are the maximum positive displacements
  • The troughs are the maximum negative displacements
  • The direction of the energy transfer is perpendicular to the direction of vibration of the particles in the wave

Longitudinal Waves

  • Longitudinal waves show areas of compressions and rarefactions

Longitudinal wave diagram, downloadable AS & A Level Physics revision notes

Diagram of a longitudinal wave

  • The compressions are areas of high pressure due to particles being close together.
  • The rarefactions are areas of low pressure due to the particles spread further apart
  • The direction of energy transfer is parallel to the direction of vibration of the particles in the wave

Worked example

The graph shows how the displacement of a particle in a wave varies with time.Which statement is correct?

A. The wave has an amplitude of 2 cm and could be either transverse or longitudinal.

B. The wave has an amplitude of 2 cm and has a time period of 6 s.

C. The wave has an amplitude of 4 cm and has a time period of 4 s.

D. The wave has an amplitude of 4 cm and must be transverse.

ANSWER:   A

Worked example - transverse and longitudinal wave (2), downloadable AS & A Level Physics revision notes

Examiner Tip

Both transverse and longitudinal waves can look like transverse waves when plotted on a graph - make sure you read the question and look for whether the wave travels parallel (longitudinal) or perpendicular (transverse) to the direction of travel to confirm which type of wave it is.

Demonstrating Waves Using a Ripple Tank

  • Waves can also be demonstrated by ripple tanks
    • These produce a combination of transverse and longitudinal waves

Ripple tank, downloadable AS & A Level Physics revision notes

Wave effects can be demonstrated using a ripple tank

  • In a ripple tank, a motorised wooden straight-edged bar produces plane (straight) waves while a small dipper produces circular waves
  • When a light is shone from above, the bright bands seen on the screen below the tank show the wave crests (wavefronts)
    • This makes it possible to measure the wavelength of the water waves and investigate the angles of reflection and refraction

  • Reflection can be investigated using plane and curved surfaces, and the angles of incidence and reflection measured with respect to the normal
  • Refraction can be investigated using a glass sheet to decrease the water depth and produce a region with a different wave speed
    • If the separation of the wavefronts decreases, this shows they are travelling more slowly and vice versa

  • Changing the angle of the wooden bar causes the wavefronts to go in a different direction
    • The ripple tank, therefore, can also be used to study interference and diffraction

You've read 0 of your 5 free revision notes this week

Sign up now. It’s free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Katie M

Author: Katie M

Expertise: Physics

Katie has always been passionate about the sciences, and completed a degree in Astrophysics at Sheffield University. She decided that she wanted to inspire other young people, so moved to Bristol to complete a PGCE in Secondary Science. She particularly loves creating fun and absorbing materials to help students achieve their exam potential.