Stationary Waves (AQA A Level Physics) : Revision Note

Katie M

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Katie M

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Stationary Waves

  • Standing waves are produced by the superposition of two waves of the same frequency and amplitude travelling in opposite directions

  • This is usually achieved by a travelling wave and its reflection

    • The superposition produces a wave pattern where the peaks and troughs do not move

  • Stationary waves store energy, unlike progressive waves which transfer energy

Stationary wave formation, downloadable AS & A Level Physics revision notes

Formation of a stationary wave on a stretched spring fixed at one end

Comparing Progressive & Stationary Waves

Stationary v Progressive Waves Table, downloadable AS & A Level Physics revision notes

Nodes & Antinodes

  • A stationary wave is made up nodes and antinodes

    • Nodes are regions where there is no vibration

    • Antinodes are regions where the vibrations are at their maximum amplitude

  • The nodes and antinodes do not move along the string

    • Nodes are fixed and antinodes only move in the vertical direction

  • The phase difference between two points on a stationary wave are either in phase or out of phase

    • Points between nodes are in phase with each other

    • Points that have an odd number of nodes between them are out of phase

    • Points that have an even number of nodes between them are in phase

  • The image below shows the nodes and antinodes on a snapshot of a stationary wave at a point in time

Nodes and antinodes, downloadable AS & A Level Physics revision notes
  • Where:

    • L is the length of the string

    • One wavelength λ is only a portion of the length of the string

Worked Example

A stretched string is used to demonstrate a stationary wave, as shown in the diagram.

WE - Nodes and Antinodes question image(1), downloadable AS & A Level Physics revision notes

Which row in the table correctly describes the length of L and the name of X and Y?

WE - Nodes and Antinodes question image(2), downloadable AS & A Level Physics revision notes

Answer: C

Worked example - nodes and antinodes (2), downloadable AS & A Level Physics revision notes

Examiner Tips and Tricks

Make sure you learn the definitions of node and antinode:

  • Node = A point of no vibration

  • Antinode = A point of maximum amplitude

In exam questions, the lengths of the strings will only be in whole or half wavelengths. For example, a wavelength could be made up of 3 nodes and 2 antinodes or 2 nodes and 3 antinodes.

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Katie M

Author: Katie M

Expertise: Physics Content Creator

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.

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