A technician is storing three different radioactive sources in a laboratory. One source emits alpha radiation, one emits beta radiation, and one emits gamma radiation. Describe the penetrating power of each type of radiation and state what material is needed to stop each one.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Radioactive sources are used in many industrial and medical applications. Safe storage and handling of these sources requires an understanding of their penetrating power.
Model answer (4 marks)
Alpha radiation has the least penetrating power – a few centimetres of air or a thin sheet of paper will stop it.
Beta radiation has intermediate penetrating power – a few millimetres of aluminium (or an equivalent thin metal sheet) will stop it.
Gamma radiation has the greatest penetrating power – it is only partially absorbed and its intensity is reduced by thick lead or thick concrete.
Beta radiation has intermediate penetrating power – a few millimetres of aluminium (or an equivalent thin metal sheet) will stop it.
Gamma radiation has the greatest penetrating power – it is only partially absorbed and its intensity is reduced by thick lead or thick concrete.
Examiner tips
- Use the exact terms ‘least’, ‘intermediate’, ‘greatest’ to match the mark scheme.
- Mention the specific materials (paper, aluminium, lead/concrete) to gain full marks.
- Keep the answer concise – one sentence per radiation type.
Common mistakes
- Confusing the order of penetrating power (alpha > beta > gamma).
- Using the wrong material (e.g., saying glass stops alpha).
- Failing to state the material needed to stop each radiation type.
Mark scheme (4 marks)
- Alpha radiation has the least penetrating power / is stopped by a few centimetres of air or a thin sheet of paper
- Beta radiation has intermediate penetrating power / is stopped by a few millimetres of aluminium (or equivalent thin metal sheet)
- Gamma radiation has the greatest penetrating power
- Gamma radiation is only partially absorbed / its intensity is reduced by thick lead or thick concrete
Key terms in this question
alpha radiation · beta radiation · gamma radiation · penetrating power
Related
- All OCR GCSE Physics A: Gateway Science (J249) revision notes →
- How to answer a "Describe" question →
- Decode the mark scheme abbreviations →
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