Quantum physics: past paper questions
Real questions on quantum physics
The newest 20 of 215 written questions, plus 1 multiple-choice. Open one to see it on the real paper.
- 9702/41 · October/November 2025 · Q8a[2]
State what is meant by a photon.
See it on the paper → - 9702/41 · October/November 2025 · Q8b(ii)[3]
Determine a value for the wavelength of the gamma radiation emitted during the decay of the uranium-238 nucleus. wavelength = m
See it on the paper → - 9702/41 · October/November 2025 · Q8b(iii)[1]
In practice, the rebound kinetic energy of the thorium nucleus is not negligible. Explain, without further calculation, how your answer in (b)(ii) compares with the true wavelength of gamma radiation emitted during the decay of the uranium-238 nucleus.
See it on the paper → - 9702/41 · October/November 2025 · Q8c[2]
Gamma radiation emitted during the decay of a sample of uranium-238 has a single wavelength. 60 Nuclei of cobalt-60 ( 27 Co) decay by beta emission, and also emit gamma radiation in the process. Suggest why there is not a single wavelength for the gamma radiation emitted during the decay of a sample of cobalt-60.
See it on the paper → - 9702/42 · October/November 2025 · Q8a[3]
Use the photon model of electromagnetic radiation to explain how the existence of spectral lines in the emission spectrum provides evidence for discrete electron energy levels in the hydrogen atom.
See it on the paper → - 9702/42 · October/November 2025 · Q8b(i)[1]
Calculate the energy, in J, of the ground state. energy = J
See it on the paper → - 9702/42 · October/November 2025 · Q8b(ii)[2]
Show that the energy difference between levels n = 1 and n = 2 is 10.2 eV.
See it on the paper → - 9702/42 · October/November 2025 · Q8b(iii)[4]
Complete Table 8.1 to show the energy differences from the ground state, and the energies of the levels up to n = 4, in the hydrogen atom. Use the space for any working. Table 8.1 level (energy difference from n = 1) / eV energy / eV n = 4 n = 3 n = 2 10.2 n = 1 0.0 –13.6
See it on the paper → - 9702/43 · October/November 2025 · Q8a[2]
State what is meant by a photon.
See it on the paper → - 9702/43 · October/November 2025 · Q8b(ii)[3]
Determine a value for the wavelength of the gamma radiation emitted during the decay of the uranium-238 nucleus. wavelength = m
See it on the paper → - 9702/43 · October/November 2025 · Q8b(iii)[1]
In practice, the rebound kinetic energy of the thorium nucleus is not negligible. Explain, without further calculation, how your answer in (b)(ii) compares with the true wavelength of gamma radiation emitted during the decay of the uranium-238 nucleus.
See it on the paper → - 9702/43 · October/November 2025 · Q8c[2]
Gamma radiation emitted during the decay of a sample of uranium-238 has a single wavelength. 60 Nuclei of cobalt-60 ( 27 Co) decay by beta emission, and also emit gamma radiation in the process. Suggest why there is not a single wavelength for the gamma radiation emitted during the decay of a sample of cobalt-60.
See it on the paper → - 9702/43 · October/November 2025 · Q9a[2]
State Wien’s displacement law.
See it on the paper → - 9702/22 · May/June 2025 · Q7b(i)[3]
Determine p. (i) p =
See it on the paper → - 9702/41 · May/June 2025 · Q8a[1]
State what is meant by the de Broglie wavelength.
See it on the paper → - 9702/41 · May/June 2025 · Q8b[2]
Calculate the de Broglie wavelength of an electron moving at a speed of 4.9 × 10 7 m s –1 . wavelength = m
See it on the paper → - 9702/41 · May/June 2025 · Q8c[2]
State one similarity and one difference between an electron and a positron. similarity: difference:
See it on the paper → - 9702/42 · May/June 2025 · Q9a[2]
State what is meant by the photoelectric effect.
See it on the paper → - 9702/42 · May/June 2025 · Q9b(i)[3]
Explain, with reference to photons, why V S depends on the frequency of the incident electromagnetic radiation.
See it on the paper → - 9702/42 · May/June 2025 · Q9b(ii)[3]
State three quantitative conclusions that can be drawn from the results in Fig. 9.2 and Fig. 9.3. Use the space for any working.
See it on the paper →
What examiners said
The identity of a photon, as a quantum of energy of electromagnetic radiation, was generally wellknown, although a significant minority of candidates omitted any reference to energy (as the quantity that is quantised) in their answer.
— Examiner report, February/March 2025, 9702/42 Q8(a) (Cambridge)
Generally well-answered, with correct answers being deduced by many candidates.
— Examiner report, February/March 2025, 9702/42 Q8(b)(i) (Cambridge)
The stronger candidates generally calculated the number of photons per unit time, from the power and the photon energy, correctly. A common mistake among some of the weaker candidates was to give an answer that is the reciprocal of the number per unit time. Candidates should consider checking whether their numerical answers have a plausible magnitude to identify errors that have been made during t...
— Examiner report, February/March 2025, 9702/42 Q8(b)(ii) (Cambridge)
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