When electromagnetic radiation is absorbed by a material, the energy carried by the radiation is transferred to the material. Explain what happens to the atoms or molecules in the material when this energy is absorbed, and describe one consequence of this energy transfer.

Eduqas GCSE Physics — 6.2 Interactions of electromagnetic radiation with matter · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

The absorbed energy raises the atoms or molecules to a higher energy state, causing them to vibrate more or move faster. This increase in kinetic energy raises the temperature of the material, so it heats up. The heated material can then re‑emit energy as electromagnetic radiation, typically in the infrared region.

Examiner tips

  • Use the word ‘raise’ or ‘increase’ to show energy transfer; mention vibration or kinetic energy; link to temperature rise; note re‑emission as IR.
  • Structure answer in clear points to match each mark scheme point.

Common mistakes

  • Failing to mention the temperature rise; confusing absorption with emission; using vague terms like ‘energy’ without specifying atoms/molecules vibrate.

Mark scheme (4 marks)

  1. The atoms or molecules gain energy (when radiation is absorbed)
  2. The atoms or molecules vibrate more / move faster / are raised to a higher energy state
  3. This causes the temperature of the material to increase / the material heats up
  4. The material may then emit radiation / re-emit energy as a different type of electromagnetic radiation (e.g. infrared)

Key terms in this question

absorbed · electromagnetic radiation · atoms · molecules

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