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AS · Practice questions · Transverse and longitudinal waves

Across, or along.

Six original Cambridge-style questions on classifying waves, compressions, and the polarisation test.

Original questions All questions on this page are original work, written in the Cambridge AS & A Level style. They are not from past papers. They test the same concepts and skills the syllabus rewards.
Keep these straight

Direction of oscillation.

01
Analysis
[2 marks]

State the difference between a transverse and a longitudinal wave, giving one example of each.

  • Transverse: oscillations perpendicular to the energy travel, for example light ✓
  • Longitudinal: oscillations along the energy travel, for example sound ✓
02
Analysis
[2 marks]

Explain why light can be polarised but sound cannot.

  • Light is transverse, so its oscillations lie in planes perpendicular to travel and one plane can be selected ✓
  • Sound is longitudinal, with oscillation along the travel direction, so there is no plane to select ✓
03
Analysis
[2 marks]

For a longitudinal sound wave, state what is meant by a compression and by a rarefaction.

  • A compression is a region where the particles are pushed close together (high pressure) ✓
  • A rarefaction is a region where the particles are spread apart (low pressure) ✓
04
Analysis
[2 marks]

Classify each as transverse or longitudinal: a water surface ripple, a sound wave, a wave on a string, a seismic P-wave (a push-pull wave).

  • Transverse: water ripple and wave on a string ✓
  • Longitudinal: sound wave and seismic P-wave ✓
05
Analysis
[2 marks]

A slinky is pushed back and forth along its length, sending a wave down it. State and justify the type of wave.

  • It is longitudinal ✓
  • The coils oscillate back and forth along the direction the wave travels, forming compressions and rarefactions ✓
06
Analysis
[2 marks]

Explain why a displacement-distance graph of a longitudinal wave can look like a transverse sine curve.

  • The graph plots particle displacement (taken as positive one way, negative the other) against position ✓
  • Plotted this way the back-and-forth displacements trace a sine curve, even though the real motion is along the travel direction ✓

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