OCR GCSE Physics A (Gateway)
OCR GCSE Physics A P6.2 Uses and Hazards Exam Questions
Free OCR GCSE Physics A exam questions for P6.2 Uses and Hazards, with a mark scheme for every pack. Covers background radiation, irradiation and contamination, effects on the body, medical uses, half-life and risk, nuclear fission and nuclear fusion.
P6.2 Uses and Hazards 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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About OCR GCSE Physics A P6.2 Uses and Hazards
P6.2 completes the P6 Radioactivity chapter of OCR Gateway Physics A. It explores the risks and benefits of radiation: the sources of background radiation, the difference between irradiation and contamination, how ionising radiation damages cells and why the choice of isotope depends on its half-life. The separate physics content covers medical uses, such as tracers and radiotherapy, and the processes of nuclear fission and fusion, including chain reactions. It applies the half-life ideas from P6.1, including the net decline in activity after a whole number of half-lives. It builds on P6.1 and links to P8.2 on energy resources. Examiners like risk evaluation questions and fission explanations.
What you need to know
- Background radiation Comes from natural sources such as rocks, radon gas and cosmic rays, and man-made sources such as medical X-rays and nuclear weapons fallout. Levels vary with location and occupation.
- Irradiation and contamination Irradiation is exposure to radiation from an external source; the object does not become radioactive. Contamination is unwanted radioactive material on or inside an object.
- Effects on the body Ionising radiation can damage cells and DNA, which can lead to cancer or cell death. Alpha sources are most dangerous inside the body; beta and gamma are more dangerous from outside.
- Half-life and use Medical tracers need short half-lives so the patient is not exposed for long, and usually emit gamma so radiation can be detected outside the body. As in P6.1, after n half-lives activity falls to (1/2)^n of the original.
- Medical uses Radioactive tracers for diagnosis, gamma radiation for killing cancer cells in radiotherapy, and gamma for sterilising equipment.
- Fission A large unstable nucleus such as uranium-235 absorbs a neutron and splits into two smaller nuclei, releasing two or three neutrons and energy. The neutrons can cause a chain reaction, which is controlled in a reactor.
- Fusion Two light nuclei join to form a heavier nucleus, releasing energy. It is the energy source of stars.
Common mistakes in P6.2 Uses and Hazards
- Saying irradiated food becomes radioactive. It does not.
- Saying alpha is always the least dangerous. It is very dangerous if the source is inside the body because it is highly ionising.
- Choosing a long half-life isotope for a medical tracer. A short half-life reduces the patient's dose.
- Mixing up fission and fusion.
- Saying background radiation only comes from nuclear power stations. Most comes from natural sources.
Try three P6.2 Uses and Hazards exam-style questions
1. Calculate the fraction of the original activity remaining after 3 half-lives. (2 marks)
Show the mark scheme answer
(1/2)^3; = 1/8 (12.5%).
2. Explain why an isotope used as a medical tracer should emit gamma radiation and have a short half-life. (4 marks)
Show the mark scheme answer
Gamma can pass out of the body to be detected; it is weakly ionising so causes less damage; a short half-life means activity falls quickly; reducing the patient's exposure, while still long enough to complete the scan.
3. Describe the process of nuclear fission. (3 marks)
Show the mark scheme answer
A uranium-235 nucleus absorbs a neutron; it splits into two smaller nuclei; releasing energy and two or three neutrons, which can cause further fissions in a chain reaction.
P6.2 Uses and Hazards FAQs
What does OCR GCSE Physics A (Gateway Science) P6.2 Uses and Hazards cover?
It covers background radiation, irradiation and contamination, health effects, medical uses, half-life in choosing isotopes, and nuclear fission and fusion.
Which paper is P6.2 examined on?
Topics P5 to P8 are assessed on Paper 2 (Foundation) or Paper 4 (Higher), which can also draw on knowledge from P1 to P4 and practical skills.
How do I evaluate the risks of using radiation?
Weigh the benefit against the harm: consider the type of radiation, whether the source is inside or outside the body, its half-life and the dose received.
