3(b) Properties of waves
Pearson Edexcel International GCSE Physics · 4PH1
Paper 1 | Whole paper: Core content, all eight topics
What all waves have in common, the wave equation, and the two behaviours every wave shows at a boundary.
Specification coverage
Topic 3 Waves (b) Properties of waves — statements 3.2–3.13
Assessment objectives: AO1, AO2, AO3. Suggested learning time: 70 minutes.
Required knowledge
- Amplitude, frequency, wavelength and period
- The difference between longitudinal and transverse waves, with examples of each
- wave speed = frequency × wavelength, v = fλ
- frequency = 1 ÷ time period
- Reflection, refraction and diffraction, and how to represent them with wavefronts
- The law of reflection and the behaviour of light at a plane mirror
Required skills
- Use the wave equation with consistent units
- Draw ray diagrams for reflection and refraction
- Explain refraction in terms of change of speed at a boundary
- Describe and evaluate the required practical: Investigate the refraction of light using rectangular blocks, semicircular blocks and triangular prisms.
How it is examined
- Multiple-choice and short-answer recall
- Calculations using the specification's relationships
- Extended open-response applying the physics to an unfamiliar situation
- Practical questions on method, variables, results and sources of error
Common mistakes
- Saying refraction happens 'because the light bends'. It bends because its speed changes at the boundary — that is the explanation, not the observation.
- Mixing units: a wavelength in centimetres with a speed in metres per second.
- Measuring angles from the surface instead of from the normal.