GCSE Physics resources
AQA GCSE Atomic structure
Irradiation is exposure to radiation from a source; contamination is radioactive material getting onto or into an object. Ionising radiation can damage cells, so risk depends on dose, time, distance, shielding and the source.
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Irradiation is exposure to radiation from a source; contamination is radioactive material getting onto or into an object. Ionising radiation can damage cells, so risk depends on dose, time, distance, shielding and the source.
Core learning content
Start with this short teaching sequence for Radiation Hazards, Contamination and Irradiation. Read the model, use the visual, then test your recall before moving into examples and exam practice.
Irradiation is exposure to radiation from a source; contamination is radioactive material getting onto or into an object. Ionising radiation can damage cells, so risk depends on dose, time, distance, shielding and the source.
Irradiation does not make an object radioactive; contamination means radioactive material is present and can spread. Ionisation can damage cells and DNA. Reduce dose by shortening exposure time, increasing distance, using suitable shielding and preventing material entering the body.
Choose a relationship because of the physical change in the question, not because it is familiar. Activity after half-lives: remaining activity = initial activity × (½)ⁿ (Bq or counts/s). Mass number: A = protons + neutrons (no unit). Atomic number: Z = number of protons (no unit). Keep the unit next to each value while you substitute.
Name the hazard, state the mechanism or route of exposure and give a control that reduces dose or prevents spread. Before writing, underline the command word and identify the information that matters. Keep a calculation as equation, substitution and answer with unit; keep an explanation as a linked chain using because, so or therefore. Finish by checking that the final sentence answers the exact context in the question and that the number, direction or conclusion agrees with the evidence given.
Retrieval practice
Answer without looking back first. The feedback explains the model, so a wrong answer still helps you learn.
Mini quiz 1
Mini quiz 2
Mini quiz 3
Try it
Which control reduces dose without confusing irradiation and contamination?
What to notice: the readout and written explanation remain available if you do not use the controls.
Worked examples
Cover the answer, attempt the method and then compare your physics language as well as the number.
This is contamination because radioactive material is on the gloves and could be transferred or taken into the body.
Minimise time near the source and maximise distance; thick shielding can also reduce the gamma radiation reaching the person.
X-rays irradiate an object but do not leave radioactive material behind, so the object does not become radioactive in normal use.
Misconception clinic
Each of these is tempting because it sounds almost right. Replace it with the precise physics before you meet it in a question.
Independent practice
Use the working space first. Reveal the guidance only after you have committed to an answer, then improve the exact part that would gain the next mark.
Radioactive material getting onto or into an object/person.
Exposure to radiation from a source.
Reduce exposure time, increase distance or use suitable shielding.
The source can remain close to cells and irradiate them from within.
Use tongs/remote handling and keep exposure time short.
It can ionise atoms in cells and damage molecules/DNA.
Questions pupils ask
Atomic-structure questions combine a model of the atom, radiation properties and careful use of nuclear notation. Always distinguish irradiation from contamination.
Read the snapshot, attempt the worked examples without looking, complete the mini quizzes and then use the practice questions to check your wording and method.
Next step
Physics sticks when you move between explanation, retrieval and application.