CIE A Level Physics
CIE A Level Physics Nuclear Physics Exam Questions
Free CIE A Level Physics exam questions for Nuclear Physics, with a mark scheme for every pack. Covers mass defect, binding energy, binding energy per nucleon, fission and fusion, radioactive decay, activity, decay constant and half-life.
Nuclear Physics exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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A-Level Physics Flashcards for 2027 Onwards
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About CIE A Level Physics Nuclear Physics
Nuclear physics is Topic 23 of the Cambridge International AS & A Level Physics (9702) syllabus. It builds on the AS Particle physics topic by applying E = mc^2 to nuclear reactions. You calculate mass defect and binding energy, interpret the graph of binding energy per nucleon to explain why fission and fusion release energy, and model radioactive decay mathematically using the decay constant, activity and half-life. Examiners commonly ask you to explain the random and spontaneous nature of decay, to calculate energy released in a reaction, and to use exponential decay equations.
What you need to know
- Mass-energy equivalence E = mc^2 relates mass and energy. In nuclear reactions, the energy released equals the decrease in mass multiplied by c^2.
- Mass defect and binding energy Mass defect is the difference between the total mass of the separate nucleons and the mass of the nucleus. Binding energy is the energy needed to separate a nucleus into its individual nucleons.
- Binding energy per nucleon The graph peaks near iron-56. Fusion of light nuclei and fission of heavy nuclei both move products towards higher binding energy per nucleon, releasing energy.
- Nature of decay Radioactive decay is random (cannot predict which nucleus will decay next) and spontaneous (not affected by external factors such as temperature). Count-rate fluctuations show randomness.
- Decay equations Activity A = λN, where λ is the decay constant. x = x0 e^(-λt) applies to N, A and count rate. Half-life t½ = 0.693/λ.
Common mistakes in Nuclear Physics
- Saying binding energy is energy stored in the nucleus. It is the energy required to separate the nucleus into free nucleons.
- Explaining fission energy release by 'breaking bonds releases energy'. Refer to the increase in binding energy per nucleon of the products.
- Forgetting to convert half-life into seconds before calculating λ for activity in becquerels.
- Mixing up random and spontaneous. Random concerns predictability; spontaneous concerns external influences.
- Using atomic masses and forgetting electrons, or mixing units of u and kg in mass defect calculations.
Try three Nuclear Physics exam-style questions
1. A sample contains 2.0 × 10^18 nuclei of an isotope with a half-life of 5.0 hours. Calculate its activity. (3 marks)
Show the mark scheme answer
t½ = 5.0 × 3600 = 1.8 × 10^4 s; λ = 0.693/1.8 × 10^4 = 3.85 × 10^-5 s^-1; A = λN = 3.85 × 10^-5 × 2.0 × 10^18 = 7.7 × 10^13 Bq.
2. The mass defect of a helium-4 nucleus is 0.0304 u. Calculate its binding energy in joules. 1 u = 1.66 × 10^-27 kg. (2 marks)
Show the mark scheme answer
Δm = 0.0304 × 1.66 × 10^-27 = 5.05 × 10^-29 kg; E = Δmc^2 = 5.05 × 10^-29 × (3.00 × 10^8)^2 = 4.5 × 10^-12 J.
3. Explain, using the binding energy per nucleon curve, why both fission and fusion release energy. (3 marks)
Show the mark scheme answer
Binding energy per nucleon peaks around iron; fission of a heavy nucleus and fusion of light nuclei both produce nuclei with greater binding energy per nucleon; total binding energy increases so mass decreases and energy is released.
Nuclear Physics FAQs
What does Cambridge AS & A Level Physics Nuclear physics cover?
It covers mass-energy equivalence, mass defect, binding energy and binding energy per nucleon, fission and fusion, and the mathematics of radioactive decay.
Which paper is Nuclear physics examined in?
It is an A Level topic assessed in Paper 4 (A Level Structured Questions), building on AS Particle physics.
What equations do I need for Nuclear physics?
Learn E = mc^2, A = λN, x = x0 e^(-λt) and t½ = 0.693/λ, and practise converting between u, kg, J and MeV.
