Describe the features of a wave, including what is meant by amplitude, wavelength, frequency, and the wave speed equation.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Waves transfer energy from one place to another without transferring matter. All waves share a set of measurable features that describe their behaviour.
Model answer (4 marks)
Amplitude is the maximum displacement of a point on the wave from its undisturbed position.
Wavelength is the distance between two successive points that are in phase, e.g. crest to crest or trough to trough.
Frequency is the number of complete waves (cycles) passing a point per second, measured in hertz (Hz).
Wave speed equals frequency multiplied by wavelength (v = f × λ), so a higher frequency or longer wavelength gives a greater wave speed.
Wavelength is the distance between two successive points that are in phase, e.g. crest to crest or trough to trough.
Frequency is the number of complete waves (cycles) passing a point per second, measured in hertz (Hz).
Wave speed equals frequency multiplied by wavelength (v = f × λ), so a higher frequency or longer wavelength gives a greater wave speed.
Examiner tips
- Use the exact definitions for amplitude, wavelength, frequency and the wave‑speed equation.
- Show the relationship v = f × λ clearly.
- Mention units (Hz for frequency, metres for wavelength, m/s for speed).
Common mistakes
- Confusing amplitude with wavelength or frequency.
- Writing the wave‑speed equation incorrectly (e.g. v = λ × f instead of v = f × λ).
Mark scheme (4 marks)
- Amplitude is the maximum displacement of a point on the wave from its undisturbed (rest/equilibrium) position
- Wavelength is the distance between two successive points that are in phase (e.g. crest to crest or trough to trough)
- Frequency is the number of complete waves (cycles) passing a point per second, measured in hertz (Hz)
- Wave speed equals frequency multiplied by wavelength (v = f × λ), so a higher frequency or longer wavelength gives a greater wave speed
Key terms in this question
amplitude · wavelength · frequency · wave speed
Related
- All WJEC GCSE Physics (Wales) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
More Features of waves questions
- A sound wave travels through air. The wave has a period of 0.002 s and a speed o…
- A student is studying waves on the surface of water in a ripple tank. The studen…
- A musician plucks a guitar string. The string vibrates and produces a sound wave…
- A student says: 'A wave with a higher frequency must have a longer wavelength.' …