Transverse and longitudinal waves
Cambridge A-Level Physics (9702) · Unit 7: Waves · 9 flashcards
Transverse and longitudinal waves is topic 7.2 in the Cambridge A-Level Physics (9702) syllabus , positioned in Unit 7 — Waves , alongside Progressive waves, Doppler effect for sound waves and Electromagnetic spectrum. In one line: In transverse waves, the oscillations are perpendicular to the direction of energy transfer (.
Marked as AS Level: examined at AS Level in Paper 1 (Multiple Choice), Paper 2 (AS Structured Questions) and Paper 3 (Advanced Practical Skills). The same content may also be assumed in Paper 4 (A Level Structured Questions).
The deck below contains 9 flashcards — 4 definitions and 5 key concepts — covering the precise wording mark schemes reward. Use the 4 definition cards to lock down command-word answers (define, state), then move on to the concept and calculation cards to handle explain, describe, calculate and compare questions.
Some cards in this deck are on other syllabus topics: 7.1 Progressive waves. Each card is labelled with its topic.
The primary difference between transverse and longitudinal waves
In transverse waves, the oscillations are perpendicular to the direction of energy transfer (
What the Cambridge 9702 syllabus says
2025-2027 syllabus, in our words · AS LevelWhat the syllabus expects you to be able to do in this topic, in plain English. For the exact wording, see the official syllabus (PDF).
- Compare longitudinal waves with transverse waves.
- Analyse and interpret graphs that represent longitudinal and transverse waves.
Also in this deck: 7.1 Progressive waves
- Describe the meaning of wave motion, using the vibrations seen in ripple tanks, ropes and springs to illustrate it.
- Understand the terms speed, wavelength, frequency, period, amplitude, displacement and phase difference, and use them correctly.
- Understand how a CRO's (cathode-ray oscilloscope's) y-gain and time-base controls are used to measure amplitude and frequency.
- Starting from how wavelength, frequency and speed are defined, derive v = fλ, the wave equation.
- Recall v = fλ and use it.
- Understand that a progressive wave transfers energy.
- For a progressive wave, recall and use the relations intensity ∝ amplitude² and intensity = power / area.
Cambridge syllabus keywords to use in your answers
These are the official Cambridge 9702 terms tagged to this section. Mark schemes credit responses that use the exact term — weave them into your answers verbatim rather than paraphrasing.
Tips to avoid common mistakes in these topics
- › Always refer to 'particle oscillations' being parallel to the 'direction of energy transfer' for longitudinal waves.
- › Specify wavelength as the distance between two adjacent wavefronts or the minimum distance between points in phase.
- › Always use the relationship Intensity ∝ (Amplitude)² for any question involving the power or brightness of a wave.
Topic 7.2 · Transverse and longitudinal waves
What is the primary difference between transverse and longitudinal waves?
In transverse waves, the oscillations are perpendicular to the direction of energy transfer (
Topic 7.2 · Transverse and longitudinal waves
Give an example of a transverse wave and describe the motion of particles within it.
Light waves are transverse waves. Particles (or, more accurately, fields) oscillate perpendicularly to the wave's direction of travel.
Topic 7.2 · Transverse and longitudinal waves
Describe how displacement and distance relate to a transverse wave's graphical representation.
In a displacement-distance graph for a transverse wave, the y-axis represents the displacement of the particles from their equilibrium position, and the x-axis represents the distance along the wave. This graph shows the wave's shape at a particular instant in time.
Topic 7.2 · Transverse and longitudinal waves
Describe how displacement and time relate to a transverse wave's graphical representation.
In a displacement-time graph for a transverse wave, the y-axis represents the displacement of a single particle from its equilibrium position, and the x-axis represents time. This graph shows how a single particle's displacement varies over time as the wave passes.
Topic 7.2 · Transverse and longitudinal waves
What do the peaks and troughs of a transverse wave represent in a displacement-distance graph?
The peaks represent the points of maximum positive displacement, while the troughs represent the points of maximum negative displacement from the equilibrium position.
Topic 7.2 · Transverse and longitudinal waves
How do compressions and rarefactions relate to longitudinal waves?
Compressions are regions of high density and pressure, where particles are close together. Rarefactions are regions of low density and pressure, where particles are spread apart.
Topic 7.2 · Transverse and longitudinal waves
Describe how displacement and distance relate to a longitudinal wave's graphical representation.
In a displacement-distance graph for a longitudinal wave, the y-axis shows each particle's displacement along the direction of travel (positive = in the direction of travel) and the x-axis shows position along the wave. Compressions are at points of zero displacement where the graph slopes downward (neighbouring particles are displaced towards them); rarefactions are at zero-displacement points where the graph slopes upward.
Topic 7.2 · Transverse and longitudinal waves
How can the wavelength of a longitudinal wave be determined from a displacement-distance graph?
The wavelength is the distance between two successive compressions (or two successive rarefactions). On a displacement-distance graph this equals the distance between two adjacent peaks, or between alternate points of zero displacement (two zero crossings where the graph slopes the same way).
Topic 7.1 · Progressive waves
Describe the relationship between the frequency of a wave and its period.
Frequency (f) is the number of complete wave cycles that pass a point per unit time, and it is measured in Hertz (Hz). Period (T) is the time taken for one complete wave cycle. They are inversely proportional: f = 1/T
Review the material
Read full revision notes on Transverse and longitudinal waves — definitions, equations, common mistakes, and exam tips.
Read NotesMore topics in Unit 7 — Waves
Transverse and longitudinal waves sits alongside these A-Level Physics decks in the same syllabus unit. Each uses the same spaced-repetition system, so progress in one informs the next.
Key terms covered in this Transverse and longitudinal waves deck
Every term below is defined in the flashcards above. Use the list as a quick recall test before your exam — if you can't define one of these in your own words, flip back to that card.
How to study this Transverse and longitudinal waves deck
Start in Study Mode, attempt each card before flipping, then rate Hard, Okay or Easy. Cards you rate Hard come back within a day; cards you rate Easy push out to weeks. Your progress is saved in your browser, so come back daily for 5–10 minute reviews until every card reads Mastered.
Study Mode
Rate each card Hard, Okay, or Easy after flipping.