A teacher demonstrates how waves behave by sending pulses along a long slinky spring stretched across the classroom floor. The teacher moves one end of the spring repeatedly from side to side at a steady rate. Describe the wave produced, explaining the meaning of frequency, wavelength, and wave speed, and state how these three quantities are related.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
The teacher creates a transverse wave, with the slinky’s coils moving up and down while the wave travels horizontally across the floor.
1. Frequency (f) is the number of complete oscillations or cycles that pass a fixed point each second.
2. Wavelength (λ) is the distance between two successive points that are in the same phase, such as crest to crest or trough to trough.
3. Wave speed (v) is the distance the wave pattern travels per second, i.e. the speed at which the wave moves through the slinky.
4. The three quantities are related by the equation v = f × λ.
1. Frequency (f) is the number of complete oscillations or cycles that pass a fixed point each second.
2. Wavelength (λ) is the distance between two successive points that are in the same phase, such as crest to crest or trough to trough.
3. Wave speed (v) is the distance the wave pattern travels per second, i.e. the speed at which the wave moves through the slinky.
4. The three quantities are related by the equation v = f × λ.
Examiner tips
- Use the word ‘transverse’ to describe the wave type. Give the definition of each term in your own words. Show the relationship v = f × λ explicitly.
Mark scheme (5 marks)
- The wave produced is a transverse wave, where the oscillations (vibrations) are perpendicular to the direction of wave travel/energy transfer.
- Frequency is the number of complete waves (oscillations/cycles) produced per second.
- Wavelength is the distance between two successive points that are in phase / the length of one complete wave (e.g. crest to crest or trough to trough).
- Wave speed is the distance travelled by the wave per second / the speed at which the wave pattern moves through the medium.
- Wave speed equals frequency multiplied by wavelength (v = f × λ).
Key terms in this question
frequency · wavelength · wave speed
Related
- All Eduqas A-Level Physics revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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