3.3.1.3
The principle of superposition: displacements add where waves overlap
Wave Types, Polarisation & Stationary Waves — AQA A-Level Physics
Key Definition
Principle of superposition — When two or more waves with the same frequency arrive at a point, the resultant displacement is the sum of the displacements of each wave.
- Applies to all types of waves: transverse and longitudinal, progressive and stationary.
- Constructive interference: waves arrive in phase, peaks align with peaks. Resultant amplitudeThe maximum displacement of a point on a wave from its equilibrium (rest) position. Measured in metres (m). is doubled.
- Destructive interference: waves arrive in antiphase, peaks align with troughs. Resultant amplitudeThe maximum displacement of a point on a wave from its equilibrium (rest) position. Measured in metres (m). is zero.
- At points between in-phase and antiphase, the resultant amplitudeThe maximum displacement of a point on a wave from its equilibrium (rest) position. Measured in metres (m). is between zero and double.