3(c) The electromagnetic spectrum
Pearson Edexcel International GCSE Physics · 4PH1
Paper 1 | Whole paper: Core content, all eight topics
One family of waves across an enormous range of wavelengths, ordered, used and — at one end — dangerous.
Specification coverage
Topic 3 Waves (c) The electromagnetic spectrum — statements 3.14–3.21
Assessment objectives: AO1, AO2. Suggested learning time: 70 minutes.
Required knowledge
- The order of the electromagnetic spectrum, by wavelength and by frequency
- That all electromagnetic waves travel at the same speed in a vacuum
- Uses of each region: radio, microwave, infrared, visible, ultraviolet, X-ray and gamma
- The detrimental effects of excessive exposure, region by region
Required skills
- Order the spectrum in either direction without hesitating
- Match a use or a hazard to the correct region and justify it by the wave's properties
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
Common mistakes
- Reversing the spectrum. Radio waves have the longest wavelength and the lowest frequency; gamma the shortest and highest.
- Saying ultraviolet 'causes cancer' without the mechanism — it damages cells and can cause mutation.
- Assuming higher frequency always means more useful. Each region is used for what its wavelength allows.