Nodes & Antinodes (OCR AS Physics): Revision Note

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

One wavelength on a stationary wave is only a proportion of its full length

• Where:

  • L is the length of the string

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

Calculating Wavelength from Nodes & Antinodes

• The wavelength λ of a stationary wave can be determined by the separation between adjacent nodes (or antinodes)

  The separation between adjacent nodes or antinodes is equal to λ / 2

• Adjacent means two nodes or antinodes that are next to each other

2 adjacent nodes are nodes that are directly next to each other