Edexcel A Level Physics
Edexcel A Level Physics Topic 11: Nuclear Radiation Exam Questions
Free Edexcel A Level Physics exam questions for Topic 11: Nuclear Radiation, with a mark scheme for every pack. Covers alpha, beta and gamma radiation, background radiation, nuclear equations, activity, decay constant, half-life, binding energy, fission and fusion.
Topic 11: Nuclear Radiation exam questions
2 question packs 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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About Edexcel A Level Physics Topic 11: Nuclear Radiation
Topic 11: Nuclear Radiation in Edexcel A Level Physics covers radioactive decay, then binding energy, fission and fusion. You compare alpha, beta and gamma radiation, account for background radiation, write balanced nuclear equations, and model decay using A = λN and N = N0 e^(-λt), including log graphs. The second part uses mass deficit and binding energy per nucleon to explain why fission and fusion release energy and why fusion needs very high temperatures and densities. The core practical investigates the absorption of gamma radiation by lead. It is assessed in Paper 2: Advanced Physics II and builds on Topic 8.
What you need to know
- Types of radiation Alpha (helium nucleus) is strongly ionising and stopped by paper; beta (electron or positron) is stopped by a few mm of aluminium; gamma (electromagnetic) is weakly ionising and reduced by thick lead.
- Background radiation Measure background count over a long time and subtract it from all readings. Sources include radon gas, rocks, cosmic rays and medical uses.
- Nuclear equations Balance nucleon and proton numbers; include neutrinos or antineutrinos in beta decay.
- Decay equations A = -dN/dt = λN; N = N0 e^(-λt); t½ = ln 2/λ. A graph of ln A against t is linear with gradient -λ. Decay is random and spontaneous.
- Binding energy Mass deficit Δm is the difference between the mass of separate nucleons and the nucleus; binding energy ΔE = c^2Δm.
- Fission and fusion Both increase binding energy per nucleon, so energy is released. Fusion needs high temperature and density so nuclei overcome electrostatic repulsion and come close enough for the strong force to act.
Common mistakes in Topic 11: Nuclear Radiation
- Forgetting to subtract background count before analysing data.
- Writing t½ = 0.693λ instead of 0.693/λ.
- Saying fission splits atoms. It splits nuclei, usually after a neutron is absorbed.
- Explaining fusion temperature in terms of 'speeding up the reaction' only. Nuclei need enough kinetic energy to overcome electrostatic repulsion.
- Saying radioactive decay is random because the count changes over time. Randomness means you cannot predict which nucleus will decay or when.
Try three Topic 11: Nuclear Radiation exam-style questions
1. A sample of iodine-131 (half-life 8.0 days) has an initial activity of 4800 Bq. Calculate its activity after 24 days. (2 marks)
Show the mark scheme answer
24 days = 3 half-lives; A = 4800 × (½)^3 = 600 Bq.
2. A sample contains 5.0 × 10^15 nuclei of an isotope with decay constant 2.0 × 10^-6 s^-1. Calculate the activity and the half-life. (3 marks)
Show the mark scheme answer
A = λN = 2.0 × 10^-6 × 5.0 × 10^15 = 1.0 × 10^10 Bq; t½ = ln 2/λ = 0.693/2.0 × 10^-6; t½ = 3.5 × 10^5 s.
3. Describe how to investigate the absorption of gamma radiation by lead. (4 marks)
Show the mark scheme answer
Measure background count rate first; place a gamma source a fixed distance from a GM tube and record count rate with no lead; add lead sheets of measured thickness (micrometer) and record count rate for each; subtract background and plot ln(corrected count rate) against thickness to find the attenuation coefficient from the gradient; handle the source with tongs and keep exposure time short.
Topic 11: Nuclear Radiation FAQs
What does Edexcel A Level Physics Topic 11: Nuclear Radiation cover?
It covers alpha, beta and gamma radiation, background radiation, nuclear equations, exponential decay, half-life, binding energy, fission and fusion.
Which paper is Topic 11 examined in?
It is assessed in Paper 2: Advanced Physics II, and like every topic it can also appear in Paper 3: General and Practical Principles in Physics.
Which core practical is in Nuclear Radiation?
Investigating the absorption of gamma radiation by lead, which uses background correction and a log graph of count rate against thickness.
