3 A type of nuclear reaction takes place at the centre of the Sun. The reaction releases thermal energy. (a) State the name of the type of nuclear reaction that takes place at the centre of the Sun. … [1] (b) Thermal energy is emitted from the surface of the Sun into space. The energy is transferred through the vacuum of space by thermal radiation. (i) Describe the radiation that is emitted from the surface of the Sun. … … … [2] (ii) State the speed of this radiation in a vacuum. speed = … [1] (iii) The Earth is 1.5 × 1011 m from the surface of the Sun. Calculate the time taken for this radiation to travel to Earth. time = … [2] (c) Explain one advantage of wearing white clothes on sunny days. … … … [2] [Total: 8]

3(a) (nuclear) fusion B1 3(b)(i) electromagnetic (waves) B1 produced by hot objects or infrared (radiation) B1 3(b)(ii) 3.0 × 108 m / s B1 3(b)(iii) (t =) x / v or 1.5 × 1011 / 3.0 × 108 C1 500 s A1 3(c) white surfaces are (good) reflectors / poor absorbers of radiation B1 less thermal energy absorbed / wearer stays cooler B1

6 Isotope X is radioactive. It decays by alpha-particle emission to a stable isotope. (a) State how a nucleus of X changes when it emits an alpha-particle. … … … [2] (b) There is a radiation detector in a laboratory where there are no radioactive samples. The detector is switched on and shows an average count rate of 22 counts / minute. (i) State why the radiation detector shows a count rate. … … [1] (ii) A sample of isotope X is placed 2 cm from the detector and the reading displayed is 8000 counts / minute. The sample is moved a distance of 10 cm from the detector. The reading returns to an average value of 22 counts / minute. Explain why the reading returns to the original value. … … … [2] (c) An alpha-particle passes into a region where there is a magnetic field. In the magnetic field, a force acts on the alpha-particle so that it follows a circular path. Fig. 6.1 shows that the particle passes through point J. path of alpha particle magnetic field J Fig. 6.1 (i) On Fig. 6.1, draw an arrow through point J to show the direction of the force on the alpha-particle at J. [1] (ii) Determine the direction of the magnetic field and mark a tick in the box (✓) that indicates this direction. to the left to the right towards the top of the page towards the bottom of the page into the page out of the page [1] (iii) Explain whether this force does work on the alpha-particle as the particle moves along the circular path. … … … [2] [Total: 9] Section B Answer two questions from this section. Answer in the spaces provided.

6(a) any two from: number of protons decreases by two number of neutrons decreases by two or number of nucleons decreases by four B2 6(b)(i) background radiation (detected) or source of background radiation mentioned (e.g. cosmic rays; radiation in the air) B1 6(b)(ii) alpha-particles are absorbed by the air (between the source and detector) B1 all the alpha-particles / radiation are absorbed (by the air between the source and detector) or alpha-particles travel less than 10 cm (in air) B1 6(c)(i) arrow through J towards centre of circular path B1 6(c)(ii) into the page (i.e. fifth box ticked) B1 6(c)(iii) force perpendicular to direction of motion or no component of velocity along line of action of force or work done = force × distance moved in direction of motion M1 no work done A1

10 Table 10.1 contains details of the nature and some properties of alpha, beta and gamma emissions. Table 10.1 alpha beta gamma nature 2 protons and 2 neutrons charge negative penetrating power stopped by 5 mm of aluminium (a) Complete Table 10.1 by filling in the missing details. [6] (b) Surgical instruments in sealed plastic bags are placed in thin plastic boxes. A conveyor belt takes the boxes close to a cobalt-60 source which sterilises the instruments. This is shown in Fig. 10.1. cobalt-60 source thick concrete boxes of surgical instruments conveyor belt Fig. 10.1 (viewed from above) The cobalt-60 source is a radioactive isotope of cobalt that emits gamma-radiation. (i) Describe what is meant by the term isotope. … … [2] (ii) Suggest a property of gamma-radiation that enables it to sterilise the instruments in the bags in the boxes. … [1] (iii) State why a source emitting only alpha-radiation cannot be used in this way. … … [1] (iv) The half-life of cobalt-60 is 5.3 years. Explain why a source with a half-life of 5.3 minutes is unsuitable for use in this application. … … [1] (c) Geiger and Marsden performed an experiment in which alpha-particles were fired at a thin film of gold. (i) Fig. 10.2 shows an alpha-particle passing close to the nucleus of a gold atom. path of alpha-particle nucleus of gold atom Fig. 10.2 Explain why the alpha-particle is deflected. … … [2] (ii) In the experiment, most of the alpha-particles pass straight through the foil without deflection. Explain, using ideas about the structure of the atom, why this happens. … … [2] [Total: 15]

10(a) alpha positive (+2) B1 alpha stopped by paper or thin metal or 3–10 cm air B1 beta electron C1 gamma electromagnetic (wave / particle) A1 gamma no charge C1 gamma not stopped (easily) or stopped by a few cm of lead or stopped a few metres of concrete A1 10(b)(i) (nuclei / atoms with) same number of protons (in nucleus) B1 different number of neutrons B1 10(b)(ii) ionisation or can penetrate (through air / boxes) or has high energy B1 10(b)(iii) stopped by box / (air-tight) bag, instruments or stopped by air B1 10(b)(iv) decays too quickly or has to be replaced often B1 10(c)(i) (alpha) repelled by nucleus B1 alpha and nucleus are positive B1 10(c)(ii) most of an atom is empty space / nucleus is only a small part of atom B1 alpha particle rarely passes close to nucleus B1

10 The isotope yttrium-90 ( 90 39 Y ) is radioactive. It is a beta-particle emitter that decays to product Q. Product Q is stable. (a) State one feature that is common to all isotopes of yttrium. … [1] (b) Describe how a neutral atom of Q differs from a neutral atom of yttrium-90. … … … … [3] (c) A sample of yttrium-90 is placed close to a radiation detector in a laboratory. There are no other radioactive samples in the laboratory. A counter records the count rate. Fig. 10.1 is a graph of the count rate plotted against time. 0 time / s time / hours 20 40 60 80 count rate counts / minute 100 0 200 300 400 500 600 700 Fig. 10.1 (i) Using Fig. 10.1, determine the average background count rate. average background count rate = … [1] (ii) Suggest two different origins for the background count. 1. … 2. … [2] (iii) Using Fig. 10.1, determine the half-life of yttrium-90. Show how the answer is obtained. half-life = … [4] (iv) Many of the points plotted in Fig. 10.1 do not lie on the best-fit line. Explain why. … … … [2] (d) A beam of beta-particles, travelling in a vacuum, enters the region between two parallel, metal plates. One plate is negatively charged and the other is positively charged. Fig. 10.2 shows the arrangement. beam of beta-particles + + + + + + – – – – – – Fig. 10.2 On Fig. 10.2, draw the path taken by the beta-particles as they travel between the two plates. [2] [Total: 15]

10(a) same number of protons (in nucleus) or same proton number or same number of electrons in a neutral atom or same atomic number B1 10(b) one more proton B1 one fewer neutron B1 one more electron B1 10(c)(i) 18 counts / minute B1 10(c)(ii) any two of: rocks / building (materials) / coal / radon space / Sun / cosmic rays weapons testing / nuclear waste B2 10(c)(iii) one count rate – 18 or one count rate – 18 calculated e.g. 74 – 18 or 56 B1 one count rate – 18 halved or one count rate – 18 reduced by factor 2N e.g. 56 / 2 or 28 or 56 / 4 or 14 B1 one count rate – 18 reduced by factor 2N + 18 e.g. 28 + 18 or 46 or 14 + 18 or 32 B1 65 hours B1 10(c)(iv) (radioactive decay is) random B1 in time or impossible to predict when a beta-particle is emitted B1 10(d) correct upward curved path between plates M1 no more than 1 cm straight at beginning A1

Cambridge O Level Physics · 5054

O-Level Physics (5054) Nuclear physics past paper questions

Revise O-Level Physics (5054) — Nuclear physics with real Cambridge past-paper questions grouped by topic, each shown with its marking scheme. Working one topic at a time targets exactly the skill each question tests.

93 free questions from 2016–2021, each with its marking scheme. Open the full topical bank to filter by subtopic, paper, and year.

Nuclear physics in O-Level Physics 5054 exams, 2020–2025

Across 2020–2025, Nuclear physics accounted for 95 questions worth 330 marks in Cambridge O Level Physics (5054) papers.

By year
Year	Questions	Marks
2020	12	39
2021	18	75
2022	12	60
2023	21	59
2024	16	48
2025	16	49

Most-tested subtopics

5.2.2 The three types of emission213 marks
5.1.2 The nucleus189 marks
5.2.3 Radioactive decay160 marks

Appears in

Paper 1 · 69 qs
Paper 2 · 26 qs

All most-tested Physics topics

2021 Oct/Nov · Paper 2 · Q3 · 8 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q6 · 9 marks
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2021 May/Jun · Paper 2 · Q10 · 15 marks
Marking scheme
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2021 Oct/Nov · Paper 2 · Q10 · 15 marks
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2021 May/Jun · Paper 1 · Q37 · 1 mark
Marking scheme
Mark scheme — 2021 Paper 1 Q37
Answer: C
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