Infrared radiation and visible light are both parts of the electromagnetic spectrum. Compare the properties of infrared radiation and visible light, and explain how infrared radiation is used in everyday applications.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
All objects emit and absorb infrared radiation. The hotter an object is, the greater the infrared radiation it emits in a given time.
Model answer (5 marks)
Both infrared radiation and visible light are electromagnetic waves travelling at the same speed in a vacuum (3 × 10⁸ m/s). Infrared has a lower frequency and a longer wavelength than visible light. Visible light can be detected by the human eye, whereas infrared cannot. Infrared radiation is used in everyday applications such as cooking food (microwave ovens), thermal imaging (night‑vision cameras) and short‑range communications (remote controls).
Examiner tips
- Use the word ‘compare’ to list similarities first, then differences; include the key points from the mark scheme.
- Mention the speed, frequency, wavelength, detection and applications to hit all 5 marks.
Common mistakes
- Confusing the direction of comparison (e.g. saying infrared has a higher frequency); forgetting to state that both are electromagnetic waves; omitting the speed of light or the eye‑detection point.
Mark scheme (5 marks)
- Both infrared radiation and visible light are transverse waves / both are electromagnetic waves
- Both travel at the same speed in a vacuum (3 × 10⁸ m/s)
- Infrared has a lower frequency / longer wavelength than visible light
- Visible light can be detected by the human eye but infrared cannot
- Infrared radiation is used for cooking food / thermal imaging / short-range communications
Key terms in this question
infrared radiation · visible light · electromagnetic spectrum
Related
- All Eduqas A-Level Physics revision notes →
- How to answer a "Compare" question →
- Decode the mark scheme abbreviations →
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