Compare transverse wave models and vibration directions
Relate local vibration to propagation for ropes, water, electromagnetic radiation and seismic S-waves.
Section P3.1 · General properties of waves
Mapped to the named 0654 section using teaching from the corresponding single-science course. A 0654-specific review of every Core and Supplement objective is still in progress. Written practice is self-checked; it does not demonstrate supervised laboratory competence or award an official Cambridge grade.
Before you begin
- Distinguish local oscillation from propagation.
- Recognise parallel and perpendicular directions.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
A wave travels right while a marker moves up and down. What is the angle relation?
What you will learn
- Know that transverse vibration is at right angles to propagation.
- Identify the specified transverse examples while retaining their model limits.
Two directions define a transverse model
In a transverse wave, local vibration is perpendicular to the propagation direction. For a rope wave travelling horizontally right, local vertical movement is one transverse example. The rope's drawn curve is a spatial shape at an instant; it is not the curved path followed by one marked material point along the rope.
If the wave travels in another direction, compare the vibration to that direction rather than assuming that 'transverse' always means vertical. A side-to-side disturbance across a suitably oriented spring can also be transverse. The defining relation is a right angle between the two directions.
Apply the selected examples carefully
Electromagnetic radiation and seismic S-waves can be modelled as transverse. In electromagnetic radiation the oscillating quantities are fields, not rope particles or air transported through space. In an S-wave, the material's local displacement is perpendicular to the wave's propagation. S-waves do not propagate as ordinary shear waves through liquids in this school account.
Water waves are also treated with a transverse surface-displacement model for the selected syllabus. Actual surface-water particle paths can have a horizontal component as well, so this useful approximation is not a universal claim of strictly vertical motion for every molecule. Use the stated model to classify the wave and explain the direction relation.
Sources for this lesson
Pause and explain
Which selected group can be modelled as transverse?
Worked example
A rope wave travels horizontally east and its marked points vibrate vertically. Classify it and compare directions.
Show the worked solution
- Propagation is eastward.
- Local vibration is vertical.
- Those directions are at right angles, so the wave is transverse.
Answer Transverse: local vibration is perpendicular to propagation.
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Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Explain why an eastward rope wave with vertical local vibration is transverse.
Give me a hint
Compare two directions rather than only naming the rope.
Compare my reasoning
- The disturbance propagates east.
- A marked point vibrates vertically.
- The directions are perpendicular.
It is transverse because vibration is perpendicular to propagation.
Look for these in your work
- Name both directions.
- State their right-angle relation.
Give the three specified transverse examples and identify the oscillating quantity for electromagnetic radiation.
Give me a hint
The electromagnetic example does not require material particles.
Compare my reasoning
- Electromagnetic radiation, water waves and seismic S-waves are the selected examples.
- Electromagnetic fields oscillate.
- The water-wave example is a surface-displacement model rather than a universal molecule-path claim.
Electromagnetic radiation, water waves and seismic S-waves; electromagnetic fields oscillate.
Look for these in your work
- Include all three examples.
- Keep the model distinction.
A transverse wave travels upward while a marked medium point oscillates left and right. Has it become longitudinal?
Give me a hint
Direction relation matters more than page orientation.
Compare my reasoning
- Propagation is upward.
- Local vibration is horizontal.
- They remain perpendicular, so it remains transverse.
No; horizontal vibration is still perpendicular to upward propagation.
Look for these in your work
- Compare the given directions.
- Avoid defining transverse as vertical.
Common mistakes
- Transverse does not mean always vertical.
- A rope snapshot is not one particle's along-rope trajectory.
- Electromagnetic fields are not a compulsory material medium.
What can you explain now?
A vibration lies at right angles to propagation. Which type is it?
Compare with the explanation
Transverse.
The direction relation, not the overall drawing orientation, defines the model.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
Classify transverse models by the direction relation and retain the specified water and field-model limits.
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.