Describe the differences between alpha particles, beta particles and gamma rays in terms of their ionising ability and penetrating power.

AQA GCSE Physics (8463) — 4.4.2 Atoms and nuclear radiation · Describe · 4 marks · View as Markdown

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

Model answer (4 marks)

Alpha particles are the most ionising; they lose energy rapidly and ionise many atoms over a short distance. They are the least penetrating – a few centimetres of air or a sheet of paper will stop them.
Beta particles are moderately ionising and have moderate penetrating power – they can pass through a few millimetres of aluminium.
Gamma rays are the least ionising but the most penetrating – they can travel long distances through air and are only partially stopped by several centimetres of lead.

Examiner tips

  • Use the terms "most", "least" and "moderate" to show the order of ionising ability and penetrating power.
  • Mention the typical shielding for each type (paper/aluminium/lead).
  • Keep the answer concise – 4 marks, so one sentence per type is enough.

Common mistakes

  • Confusing the order of ionising ability (e.g. saying beta > alpha).
  • Forgetting to state the shielding material for each radiation type.

Mark scheme (4 marks)

  1. Alpha particles are the most (highly) ionising / have the greatest ionising ability
  2. Gamma rays are the least ionising / have the lowest ionising ability
  3. Alpha particles are the least penetrating / are stopped by a few centimetres of air or a sheet of paper
  4. Gamma rays are the most penetrating / can travel a long distance through air / are only partially stopped by several centimetres of lead

Key terms in this question

alpha particle · beta particle · gamma ray · ionising · penetrating power

Related

More Atoms and nuclear radiation questions

▶ Try answering this question with AI marking (free) →