A student uses a rope to demonstrate wave properties. She fixes one end of the rope to a wall and moves the other end up and down repeatedly at a steady rate. The waves produced have a wavelength of 0.4 m and travel along the rope at 2.0 m/s. Describe the key features of the wave she has produced and explain how the wave speed, frequency and wavelength are related.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Model answer (5 marks)
1. The wave is a transverse wave, with the rope moving up and down perpendicular to the direction of propagation.
2. The wavelength (λ) is 0.4 m, the distance between two successive crests (or troughs).
3. The wave travels along the rope at a speed (v) of 2.0 m s⁻¹.
4. The frequency (f) is the number of complete waves passing a fixed point per second.
5. The wave equation relates these quantities: v = f × λ, so f = v/λ = 2.0 m s⁻¹ ÷ 0.4 m = 5 Hz.
2. The wavelength (λ) is 0.4 m, the distance between two successive crests (or troughs).
3. The wave travels along the rope at a speed (v) of 2.0 m s⁻¹.
4. The frequency (f) is the number of complete waves passing a fixed point per second.
5. The wave equation relates these quantities: v = f × λ, so f = v/λ = 2.0 m s⁻¹ ÷ 0.4 m = 5 Hz.
Examiner tips
- Use the word ‘transverse’ to describe the wave type. State λ, v and f explicitly. Show the calculation for f. Link the wave equation to the given values.
Common mistakes
- Confusing transverse with longitudinal. Using the wrong formula (e.g., v = λ/f). Forgetting to calculate the frequency. Mis‑labeling crests and troughs.
Mark scheme (5 marks)
- The wave produced is a transverse wave
- Wavelength is the distance between two adjacent crests (or troughs), or the length of one complete wave cycle
- Frequency is the number of complete waves (oscillations) passing a point per second
- Correct statement of the wave equation: wave speed = frequency × wavelength
- Correct calculation or statement that the frequency of the wave is 5 Hz (using 2.0 = f × 0.4)
Key terms in this question
wavelength · frequency · 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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