IGCSE Physics: Atomic and Nuclear Physics
Nuclear physics is a gift to anyone who learns the definitions properly. The examiners recycle the same questions year after year: define half-life, compare α/β/γ, balance a nuclear equation, describe one real-world use of radiation. Know the script and this topic becomes free marks.
Practice this topic by speaking your answer
Record a past-paper style answer, get an instant Whisper transcript and AI mark-scheme feedback tuned to CIE 0625 / Edexcel 4PH1.
Open voice practiceWhat you need to master
- 1Structure of the atom, nucleons, atomic number Z, mass number A.
- 2Isotopes: same Z, different A, and examples.
- 3Alpha, beta (minus) and gamma radiation — nature, ionising and penetrating powers.
- 4Balanced nuclear equations for α and β decay.
- 5Half-life: definition, graph interpretation and calculations.
- 6Background radiation, sources and safety precautions.
- 7Uses of radioactivity: medical tracers, sterilisation, dating.
Key formulas
A = Z + N
After n half-lives: activity = initial / 2ⁿ
Examiner tips
- •For half-life, say "the time taken for HALF the radioactive NUCLEI to decay" — not "half the atoms", not "half the sample".
- •Always give the stopping material: alpha → paper, beta → few mm aluminium, gamma → thick lead / concrete.
- •In nuclear equations check that mass number and atomic number both balance.
Common mistakes to avoid
- •Treating half-life as a constant countdown rather than a statistical property.
- •Forgetting that β⁻ decay turns a neutron into a proton, increasing Z by 1.
- •Claiming gamma radiation has no effect on living tissue because it is "only waves".
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