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Half-life and activity of radioactive sources
Practice Questions

40 AQA GCSE Physics questions on Half-life and activity of radioactive sources, each with instant feedback and a full examiner-style mark scheme.

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✨ Revision guide includes key terms, worked examples and exam technique for Half-life and activity of radioactive sources.

Try 2 sample questions on Half-life and activity of radioactive sources

Question 1 · 1 mark · Difficulty 1/3

What is meant by the 'activity' of a radioactive source?

  1. The time taken for half the atoms to decay
  2. The energy released by the source each second
  3. The number of radioactive atoms present in the source
  4. The number of nuclear decays per second in the source
Show answer & explanation
✓ Answer: D — The number of nuclear decays per second in the source
Activity is defined as the number of nuclear decays (disintegrations) per second, measured in becquerels (Bq). Option C describes the count of atoms, not the rate of decay. Option B describes power output, which is not activity. Option A is the definition of half-life, a related but distinct concept.
Question 2 · 1 mark · Difficulty 1/3

Which statement correctly defines the half-life of a radioactive isotope in terms of its activity?

  1. The time taken for the count rate from a source to double
  2. The time taken for the activity of a source to fall to zero
  3. The time taken for half of the atoms in a sample to be created
  4. The time taken for the activity of a source to fall to half its starting value
Show answer & explanation
✓ Answer: D — The time taken for the activity of a source to fall to half its starting value
Award 1 mark. Half-life can be given either as the time for half the unstable nuclei to decay or as the time for the activity to halve, because activity is proportional to the number of undecayed nuclei. Activity approaches zero but never quite reaches it.
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AQA GCSE Physics: Half-life and activity of radioactive sources FAQ

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Are the Half-life and activity of radioactive sources questions aligned to the official AQA GCSE Physics syllabus?
Every question is written against the published AQA GCSE Physics specification, including the exact command words (state, describe, explain, calculate, evaluate, etc.), mark allocations, and difficulty tier you'd see on a real AQA paper. Explanations are written in the style of official examiner mark schemes — they tell you what is being awarded marks and why distractors are wrong, not just whether you got it right. The bank is continually refined to match the latest syllabus updates from AQA.
How is Half-life and activity of radioactive sources typically tested on AQA GCSE Physics papers?
Half-life and activity of radioactive sources appears across multiple question types on real AQA GCSE Physics papers — most commonly as multiple-choice questions in the objective section, structured short-answer questions in the main paper, and occasionally as part of an extended response. Kramizo's practice bank reflects that mix: 4-option MCQs, true/false statements, fill-in-the-blank key terms, multi-select questions, and ordering questions. Working through the bank gives you exposure to every question style examiners actually use.

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