WPH15 Physics Unit 5 past-paper analysis, Oct 2020 – Jun 2026
Edexcel IAL Physics Unit 5: Thermodynamics, Radiation, Oscillations and Cosmology (WPH15). 18 papers, updated 3 October 2026.
Scope and method
This covers all 18 current-specification WPH15 papers from October 2020 to June 2026: 1,620 marks, with every question part tagged by topic, method and command word. The predictions at the end follow from these patterns; they are not inside information.
- Papers: October 2020, then January, June and October of 2021 to 2025, then January and June 2026. The October 2020 paper has a June 2020 cover, but its mark scheme is WPH15_01_2010_MS, so it is counted as the October 2020 sitting.
- Excluded: June and October 2019, which are the old WPH05 specification (80 marks, 1 h 35 min).
- Method: each question part, MCQs included, was matched to its mark scheme and tagged with one of 11 topic areas, the equation route or explanation the mark scheme rewards, and its command word. Mixed questions were split by marking point, so read per-topic figures as roughly ±2 marks.
- Counts: “in 17 of 18” means the method was needed in a Section B question in 17 papers, unless MCQs are stated as included.
- Other sources: Pearson’s published October grade boundaries and the June 2025 WPH15 examiners’ report (linked where used).
Paper format and October grade boundaries
WPH15 is 1 h 45 min for 90 marks: 10 MCQs, then 9 to 11 structured questions numbered from Q11, one of them an asterisked 6-mark extended response. The A boundary in October sittings has ranged from 54 to 71 marks.
- Section A: 10 MCQs. The mean in June 2025 was 7 out of 10.
- Section B: 80 marks across Q11 to Q19, Q20 or Q21. Four of the last five October papers had 11 questions. Question totals run from 2 marks up to 18 (January 2022 Q19).
- The 6-marker: marked on indicative content (up to 4 marks) plus linkage of the points into a sustained argument (up to 2 marks).
- Formula sheet: the Unit 5 page plus the Unit 1, 2 and 4 pages. The data list includes k, σ, u = 1.66 × 10−27 kg, G and g = 9.81 N kg−1.
| October series | A* | A | B | C | D | E |
|---|---|---|---|---|---|---|
| October 2024 | 79 | 71 | 63 | 55 | 47 | 40 |
| October 2022 | 63 | 54 | 48 | 43 | 38 | 33 |
| October 2021 | 65 | 54 | 49 | 44 | 39 | 34 |
Raw marks out of 90, from Pearson’s published boundary documents. Because the A boundary rose 17 marks between 2022 and 2024, a mock score of 72 or more is the safe target for an A.
Topic weighting
Oscillations carry the most marks, 15 of 90 a paper on average, then radioactivity (12.5) and gravity (11.5). Grouped, astrophysics and cosmology take about 24 marks a paper, nuclear physics about 22, and heating with gases about 16.
Oscillations average 15 marks a paper, and every Unit 5 topic scores in all 18 papers
Marks per topic in each WPH15 paper (out of 90), sorted by average. October papers have bold headings; the outlined column is June 2026.
| Topic | Oct 20 | Jan 21 | Jun 21 | Oct 21 | Jan 22 | Jun 22 | Oct 22 | Jan 23 | Jun 23 | Oct 23 | Jan 24 | Jun 24 | Oct 24 | Jan 25 | Jun 25 | Oct 25 | Jan 26 | Jun 26 | Avg |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Oscillations | 17 | 19 | 17 | 11 | 12 | 18 | 19 | 16 | 18 | 12 | 9 | 16 | 19 | 20 | 14 | 12 | 7 | 14 | 15.0 |
| Radioactivity | 9 | 16 | 17 | 11 | 13 | 9 | 20 | 8 | 14 | 11 | 15 | 17 | 7 | 8 | 15 | 9 | 11 | 15 | 12.5 |
| Gravity and orbits | 9 | 14 | 10 | 15 | 8 | 13 | 10 | 17 | 5 | 19 | 10 | 11 | 9 | 11 | 10 | 11 | 17 | 8 | 11.5 |
| Binding and fusion | 7 | 5 | 12 | 15 | 9 | 8 | 6 | 2 | 13 | 8 | 21 | 9 | 13 | 5 | 5 | 11 | 16 | 6 | 9.5 |
| Heating | 14 | 6 | 6 | 4 | 6 | 10 | 5 | 5 | 13 | 13 | 6 | 9 | 10 | 17 | 7 | 6 | 9 | 11 | 8.7 |
| Gases | 13 | 6 | 7 | 6 | 6 | 5 | 6 | 13 | 6 | 7 | 6 | 5 | 7 | 7 | 7 | 12 | 8 | 8 | 7.5 |
| Doppler and Hubble | 5 | 10 | 6 | 11 | 9 | 10 | 8 | 13 | 3 | 11 | 7 | 7 | 9 | 6 | 2 | 3 | 5 | 8 | 7.4 |
| Distances | 5 | 4 | 7 | 6 | 7 | 7 | 7 | 11 | 5 | 1 | 5 | 3 | 4 | 8 | 10 | 8 | 3 | 5 | 5.9 |
| Wien and Stefan | 4 | 2 | 5 | 8 | 5 | 6 | 8 | 4 | 8 | 4 | 8 | 3 | 7 | 4 | 7 | 6 | 8 | 7 | 5.8 |
| HR and evolution | 1 | 7 | 1 | 3 | 12 | 2 | 1 | 1 | 5 | 4 | 3 | 8 | 5 | 1 | 11 | 8 | 1 | 8 | 4.6 |
| Carry-over | 6 | 1 | 2 | – | 3 | 2 | – | – | – | – | – | 2 | – | 3 | 2 | 4 | 5 | – | 1.7 |
The big swings come from which topic gets the longest question that session: binding energy and fusion took 21 marks in January 2024, and the HR diagram 12 in January 2022 and 11 in June 2025.
Technique-level breakdown
The paper is built from a small set of fixed methods: twelve of them appear in 15 or more of the 18 papers. Each table lists the method the mark scheme rewards, how many papers needed it in Section B, and where. MCQ-only appearances are noted separately.
Heating, latent heat and internal energy
| Method or route | Papers | Where |
|---|---|---|
| ΔE = mcΔθ | 18 of 18 | Every paper |
| ΔE = LΔm (melting, boiling, evaporating) | 15 of 18 | All except Oct 22, Oct 25 and Jan 23 (Jan 23 as an MCQ only) |
| Mass first from ρ = m/V (pools, ice blocks, tanks, ice cream) | 11 | Jun 21, Jun 22, Oct 22, Jan 23, Jun 23, Jun 24, Jan 25, Jun 25, Oct 25, Jan 26, Jun 26 |
| Heater or source power: E = Pt, efficiency, rate of energy transfer | 9 | Oct 20, Jan 21, Jun 21, Oct 21, Oct 23, Jun 24, Jan 25, Jan 26, Jun 26 |
| Energy balance (energy lost by hot = energy gained by cold), then deduce a final temperature | 4 | Oct 20, Jan 22, Oct 24, Oct 25 |
| Flow rate: mass per second × c × Δθ | 2 | Oct 22, Jun 26 |
| Explaining energy transfer during a change of state (potential energy changes, kinetic energy constant) | 3, plus 2 MCQs | Jun 23 (6-marker), Jan 24, Jun 25; MCQs Oct 20, Jan 24 |
| Energy losses or errors in heating and latent-heat experiments | 2, plus 3 MCQs | Jan 23, Jan 25; MCQs Jan 22, Jan 26, Jun 26 |
| Thermistor calibration method (core practical 12) | 2 | Oct 23 (6-marker), Oct 24 (6 marks, point-marked) |
| Comparing coolants by specific heat capacity | 1 | Jun 26 |
Ideal gases and kinetic theory
| Method or route | Papers | Where |
|---|---|---|
| pV = NkT, with a separate mark for converting °C to K | 18 of 18 | Every paper |
| Two states of a fixed mass of gas (p/T, V/T or pV constant) | 9 | Jun 21, Jan 22, Jan 23, Oct 23, Jan 24, Oct 24, Jan 25, Oct 25, Jun 26 |
| Mean kinetic energy from ½m⟨c2⟩ = 3/2 kT, or internal energy 3/2 NkT | 8 | Oct 21, Jan 22, Jun 22, Oct 23, Oct 24, Jun 25, Jan 26, Jun 26 |
| Mass or density of a gas via N × mass of one molecule | 5 | Oct 22, Jan 24, Jun 24, Jun 25, Jan 26 |
| Volume from 4/3 πr3 or from a circumference (not on the formula sheet) | 4 | Oct 20, Oct 24, Jun 25, Oct 25 |
| Kinetic-theory explanation of a pressure change | 4 | Oct 20 (6-marker), Jun 21 (4 marks), Jan 23 (6-marker), Oct 25 (6-marker) |
| Pressure above atmospheric, or pressure at depth | 2 | Oct 20, Oct 24 |
| Deriving U = 3/2 pV | 1 | Jun 26 |
| Spread of molecular speeds (why some gas escapes a planet) | 1 | Jan 23 |
Gas MCQs appeared in 12 of the 18 papers. Six tested rms-speed or mean-square-speed ratios between gases at the same temperature, and the rest tested the ideal-gas assumptions or the fact that mean kinetic energy depends only on temperature.
Radioactivity and decay
| Method or route | Papers | Where |
|---|---|---|
| λ = ln 2/t½ inside a decay calculation | 18 of 18 | Every paper |
| Completing a nuclear equation (top line and bottom line, 1 mark each) | 17 of 18 | All except Oct 23 |
| N = N0e^(−λt) or A = A0e^(−λt), forwards or solved for t with ln | 15 | Oct 20, Jan 21, Oct 21, Jan 22, Jun 22, Oct 22, Jun 23, Oct 23, Jun 24, Oct 24, Jan 25, Jun 25, Oct 25, Jan 26, Jun 26 |
| A = λN (activity to number of nuclei, or back) | 9, plus 1 MCQ | Jan 21, Jun 21, Oct 22, Jan 23, Oct 23, Jun 24, Jun 25, Oct 25, Jun 26; MCQ Oct 21 |
| Choosing or explaining a radiation from its properties: ionising vs penetrating, range, uses, hazards | 10 | Oct 20, Jun 21 (incl. the 6-marker), Oct 21, Jan 22, Oct 22, Jan 24, Jun 24, Jan 25, Jan 26, Jun 26 |
| Sample mass from activity, or activity from mass, via u = 1.66 × 10−27 kg | 5 | Oct 22, Jan 23, Oct 23, Jun 24, Jun 26 |
| Absorption: μ from a ln graph or an exponential, half-value thickness, % transmission (core practical 15) | 4, plus 3 MCQs | Jan 21 (6 marks), Oct 21, Jan 24, Jun 24; MCQs Oct 20, Jan 23, Jun 25 |
| Why beta particles have a range of energies (three particles share the energy) | 3 | Jan 21, Oct 21, Oct 22 |
| Power from activity × energy per decay | 2 | Jun 21, Jun 25 (a related energy-over-time calculation in Oct 23) |
| Cloud-chamber tracks: thickness from ionising ability, shape from mass | 2 | Jun 23, Jun 25 |
| Speed of an emitted particle from its energy (eV to J, then ½mv2) | 2 | Oct 20, Jun 23 |
| Background count: subtract it, or make it more reliable | 1, plus 7 MCQs | Jun 24; MCQs in Oct 20, Jun 21, Jan 22, Jan 23, Jun 23 and two in Jan 26 |
“Random” vs “spontaneous” was an MCQ in five papers (Oct 22, Jan 24, Jun 24, Jan 26, Jun 26).
Mass defect, binding energy, fission and fusion
| Method or route | Papers | Where |
|---|---|---|
| Energy from a mass difference: u to kg, ΔE = c2Δm, J to MeV | 17 of 18 | All except Jun 26 (MCQ only). Ten of these were decay or reaction energies: Jan 21, Jun 21, Oct 21, Jun 22, Oct 22, Jun 23, Oct 23, Jun 24, Jun 25, Jan 26 |
| Fusion conditions: high temperature to overcome repulsion, high density for collision rate | 7, plus 5 MCQs | Oct 20 (on Earth, 4 marks), Oct 21 (6-marker), Jun 23 (4), Jan 24 (6-marker), Oct 24 (6-marker), Jan 26 (6-marker), Jun 26 (4); MCQs Jun 21, Jun 22, Oct 22, Oct 23, Jun 26 |
| Defining fission, or explaining why fission and fusion release energy | 6 | Jun 21, Oct 22, Jun 23, Jan 24, Oct 25, Jan 26 |
| Momentum conservation in a decay: daughter recoil, alpha takes most of the kinetic energy | 6 | Oct 21, Jan 22, Jun 22, Oct 22, Oct 23, Jan 26 |
| Binding energy and binding energy per nucleon from proton and neutron masses | 5 | Jun 21, Jan 24, Oct 24, Jan 25, Oct 25 |
| Energy released, read off the binding-energy-per-nucleon graph | 2 | Jun 23, Jan 24 |
| Stellar-scale energy: the Sun’s mass loss from its luminosity, or hydrogen used over its lifetime | 2 | Oct 20, Jun 24 |
| Sketching the binding-energy-per-nucleon curve, with iron-56 at the peak | 1, plus 8 MCQs | Jun 21; MCQs Oct 20, Oct 21, Jan 22, Oct 22, Jan 23, Oct 23, Jan 25, Jun 25 |
Oscillations, resonance and damping
| Method or route | Papers | Where |
|---|---|---|
| Period from T = 2π√(m/k) or T = 2π√(l/g) | 15 of 18; 18 of 18 with MCQs | All except Jan 22, Oct 22 and Oct 25, which had it as an MCQ |
| SHM definition, or explaining why a motion or graph is SHM | 13 | Oct 20, Jan 21, Jun 21, Oct 21, Jun 22, Oct 22, Jun 23, Oct 23, Jun 24, Jan 25, Jun 25, Oct 25, Jun 26 |
| Resonance explained in context | 11, plus 4 MCQs | Oct 20, Jan 21, Jan 22, Jun 22 (6-marker), Oct 22, Jan 23, Jun 23, Jun 24, Oct 24, Jan 25 (6-marker), Jun 26; MCQs Jun 21, Jun 24, Jun 25, Oct 25 |
| Maximum speed v = ωA (from v = −Aω sin ωt with sin ωt = 1) | 10 | Oct 20, Jan 21, Jan 22, Jun 23, Oct 23, Oct 24, Jan 25, Jun 25, Oct 25, Jan 26 |
| Spring constant from a static stretch, mg = kΔx | 8 | Oct 20, Jun 21, Oct 21, Jun 22, Jan 23, Jan 24, Oct 24, Jun 26 |
| Damping: work done against resistive forces, energy dissipated | 7, plus 7 MCQs | Oct 20, Jan 23, Oct 23, Jun 24, Jan 25 (6-marker), Jun 25, Jun 26; MCQs in Jun 23, Oct 24, Jan 25, Oct 25 and Jan 26, four of them on plastic deformation |
| Maximum kinetic energy ½m(ωA)2, or energy read off a graph | 6 | Oct 20, Jan 23, Oct 24, Jan 25, Oct 25, Jan 26 |
| Sketching displacement, velocity, acceleration or kinetic-energy graphs | 6, plus about 12 MCQs | Oct 20, Jun 21, Jan 22, Jan 23, Jan 25, Oct 25 |
| Period read off a graph over several cycles, or from oscillations per minute | 4 | Jun 21, Oct 22, Jun 25, Oct 25 |
| a = −ω2x, including ω from the gradient of an a–x graph | 4 | Jan 21, Jan 22, Oct 22, Jan 25 |
| Graph method for k: T2 against m has gradient 4π2/k (core practical 16), or timing many oscillations | 2 | Jun 21, Jun 23 |
| Other: elastic vs plastic, maximum load when oscillating, losing contact, loose particles in a shaker | 4 | Jan 21, Oct 21, Jun 22, Oct 22 |
Gravitational fields and orbits
| Method or route | Papers | Where |
|---|---|---|
| Orbit equation GMm/r2 = mω2r (or mv2/r) for T, r, v or M | 16 of 18 | All except Oct 20 and Jan 23 |
| g = GM/r2, including ratios between planets | 12 | Oct 20, Jan 21, Oct 22, Jan 23, Oct 23, Jan 24, Jun 24, Oct 24, Jan 25, Jun 25, Oct 25, Jan 26 |
| Potential V = −GM/r and ΔEgrav = mΔV, including escape velocity and V–r graphs | 12, plus 4 MCQs | Oct 20, Jan 21, Jun 21, Oct 21, Jun 22, Jan 23, Oct 23, Jun 24, Jan 25, Jun 25, Oct 25, Jan 26; MCQs Oct 22, Jun 23, Oct 24, Jun 26 |
| Explaining orbits and fields in words: weightlessness, lower orbit means shorter period, the Sun losing mass, equipotential spacing, field comparison, drag | 9 | Oct 20, Jan 21, Jun 21, Oct 21, Oct 23, Jan 24, Jun 24, Jan 26, Jun 26 |
| Newton’s law F = GMm/r2 for a force | 3 | Oct 22, Jan 23, Oct 23 |
| Deriving T2 ∝ r3, or Kepler’s constant 4π2/GM | 3 | Jan 22, Jun 22, Jun 24 |
| Escape velocity v = √(2GM/r) | 2 | Jan 23, Oct 25 |
| Geostationary orbit: 24-hour period, height above the equator | 2 | Jun 25, Oct 25 |
| Mass from density × 4/3 πr3 | 2 | Jan 23, Oct 23 |
| Dark matter from orbital speeds or periods | 2 | Jan 22, Jun 24 |
Stars: Wien and Stefan
| Method or route | Papers | Where |
|---|---|---|
| Wien’s law λmax T = 2.898 × 10−3 m K | 17 of 18 | All except Jan 21 (MCQ only) |
| Stefan–Boltzmann L = σAT4 with A = 4πr2 | 16 of 18 | All except Jan 21 and Jun 21 (MCQs only) |
| Combining with I = L/4πd2 for the intensity at a planet or at Earth | 6 | Oct 20, Jan 23, Jun 24, Oct 24, Jun 25, Jun 26 |
| “Assess the claim” about a star’s radius or luminosity: Wien gives T, Stefan gives r or L, then compare and conclude | 5 | Jan 22, Jun 23, Oct 23, Oct 25, Jan 26 |
| Peak read off a frequency graph, converted with λ = c/f before Wien | 3 | Oct 22, Oct 24, Jun 25 |
| Why a star whose peak is in the infrared still looks red (a range of wavelengths is emitted) | 2 | Oct 21, Jan 26 |
| Limits of the black-body model (a filament isn’t a perfect black body) | 1 | Jan 25 |
| Absorption lines from discrete energy levels (Unit 2 carry-over) | 1 | Jan 25 |
HR diagram and stellar evolution
| Method or route | Papers | Where |
|---|---|---|
| Placing a star or region on the diagram (the Sun at about 6000 K and L = 1) | 7 | Oct 20, Jan 21, Jun 22, Oct 23, Oct 24, Jun 25, Oct 25 |
| Stellar evolution in words: main sequence → red giant → white dwarf | 6 | Jan 21 (6-marker), Jan 22 (6-marker), Jan 24 (3 marks), Jun 24 (6-marker), Jun 25 (6-marker, plus a drawn path), Jun 26 (6-marker) |
| Labelling the temperature axis: reversed and logarithmic | 4 | Jan 22, Jun 23, Oct 25, Jun 26 |
| A cluster’s age from its diagram | 3 | Jan 21 (6-marker), Jun 23, Oct 25 |
| Main-sequence definition (hydrogen fusion in the core) | 2 | Oct 21, Oct 23 |
| Why massive stars leave the main sequence sooner (hotter core, faster fusion) | 1 | Jun 25 |
| White dwarf properties | 1 | Oct 25 |
HR MCQs appeared in 10 of the 18 papers, mostly on possible evolutionary paths and how radius, density and temperature change between stages.
Distances: parallax and standard candles
| Method or route | Papers | Where |
|---|---|---|
| Describing the standard-candle method: locate it, measure its intensity, apply the inverse square law | 7 | Jan 22, Oct 22 (6-marker), Jan 23, Jun 23, Jan 24, Jun 25, Oct 25 |
| Distance or luminosity from I = L/4πd2 on its own | 5 | Oct 20, Jun 21, Oct 21, Jun 22, Jan 25 |
| Parallax: its limit, or d = r/θ | 5 | Jan 22, Jun 22, Jan 23, Jun 25, Jun 26 |
| Defining a standard candle (an object of known luminosity) | 4, plus 1 MCQ | Jun 21, Jan 23, Jan 25, Jun 25; MCQ Oct 21 |
| Describing trigonometric parallax | 3 | Oct 21, Jan 23, Oct 25 |
| Effects on a measured distance (dust lowers the intensity) or new kinds of candle (lasers) | 2 | Jan 21, Oct 25 |
| Cepheid period–luminosity graph | 1 | Jan 25 |
Parallax was also an MCQ in five papers (Jun 23, Oct 23, Jan 24, Jun 24, Jan 25), and inverse-square intensity ratios in five more.
Doppler, Hubble and dark matter
| Method or route | Papers | Where |
|---|---|---|
| Doppler shift z = Δλ/λ ≈ Δf/f ≈ v/c for a speed, plus towards or away | 15 of 18 | All except Jan 22, Jun 23 and Jun 25 (MCQs only). Three used a frequency shift: Jan 24, Oct 25, Jun 26 |
| Hubble’s law for a distance, or describing how the most distant galaxies are measured | 5 | Jan 21, Oct 21, Jan 23, Oct 24, Jun 26 |
| Age of the universe from 1/H0, or converting H0 from km s−1 Mpc−1 | 4, plus 6 MCQs | Oct 21, Jun 22, Oct 22, Jan 24; MCQs Jun 21, Oct 22, Jun 23, Jan 25, Jun 25, Oct 25 |
| Doppler from rotation or an orbit (v = 2πr/T) | 4 | Oct 20, Oct 21, Oct 23, Jan 25 |
| Redshift defined or explained | 4 | Jan 21, Oct 21, Oct 23, Oct 24 |
| Dark matter defined, with evidence | 4, plus 1 MCQ | Jan 22, Jan 23, Jun 24, Jan 26; MCQ Jan 21 |
| Fate of the universe vs critical density | 2, plus 3 MCQs | Jan 22, Jan 23; MCQs Jun 23, Oct 24, Jan 26 |
| Validity of Hubble’s law (scatter, uncertainty) | 1 | Oct 23 |
| Very large redshift moves visible light into the infrared | 1 | Oct 22 |
Command words and question styles
“Calculate” and “explain” dominate Section B, but the marks most often dropped sit on the evaluative words (deduce, assess, evaluate), whose last mark needs a comparison and a conclusion.
| Command word | Prompts across 18 papers | Papers using it | What the final mark needs |
|---|---|---|---|
| Calculate | 115 | 18 | Equation, substitution, answer with unit; errors carry forward (ecf) |
| Explain | 95 | 18 | One physics idea plus its reason per mark, naming the law or principle |
| Show that | 55 | 17 | Every step visible; answer to one more significant figure than the value given |
| Deduce | 34 | 17 | Calculate, compare two values from the question, write the conclusion |
| State | 28 | 16 | Standard definition wording (SHM, standard candle, main sequence, redshift) |
| Assess | 24 | 13 | As for deduce: the final mark is the comparison and the conclusion |
| Complete (an equation) | 20 | 17 | Top and bottom lines balanced |
| Determine | 19 | 13 | Usually from a graph: a gradient, intercept or reading |
| Describe | 17 | 12 | Method steps in order, with technical verbs (“locate”, “measure the intensity”) |
| Suggest | 13 | 11 | Physics applied to an unfamiliar context; any reasoned answer |
| Evaluate | 10 | 7 | Comparison with a value given or derived in the question, then a judgement |
| Sketch, add, label, mark, draw | 17 | 11 | Graph shapes, HR-diagram axes, positions on diagrams |
| Criticise | 1 | 1 (Jun 25) | Say what is wrong with the given statement, then give the physics |
Counts are occurrences in Section B text, so treat them as ±2.
- Every Section B question is set in a real context (airbags, scuba tanks, bridges, a pacemaker, a space probe, a speed camera). The data needed sits in the stem, sometimes several lines up.
- Parts chain together: λ → N → mass; Wien → T → Stefan → radius; k → T → vmax. A “show that” value is given so later parts stay accessible.
- Derivations recur: T2 ∝ r3 (Jun 22, Jun 24), Kepler’s constant (Jan 22), escape velocity (Jan 23, Oct 25), U = 3/2 pV (Jun 26).
- Graph work: reading λmax or a period, gradients of ln graphs and T2–m graphs, intercepts.
- Shape is shifting towards more short questions: Oct 25 and Jan 26 both opened Section B with two 2-mark questions, and four of the last five October papers had 11 structured questions.
Every 6-mark question
Four topics account for 14 of the 18 six-markers: stellar evolution (5), fusion conditions (4), kinetic-theory pressure (3) and resonance (2). The October slots went to kinetic theory (2020, 2025), fusion (2021, 2024), standard candles (2022) and thermistor calibration (2023).
Marking: 6 indicative-content points = 4 marks, 4–5 = 3, 2–3 = 2, 1 = 1. Linkage adds up to 2 more marks, but only with 5–6 points (1 mark with 3–4 points), so an unlinked list of six points scores 4.
| Paper | Question | Topic | Indicative content (the six points) |
|---|---|---|---|
| Jun 26 | Q16(b) | The Sun’s evolution, positions A and B on an HR diagram | Hydrogen fusion in the core at A; core hydrogen used up, so the fusion rate falls; core contracts under gravity; temperature rises and helium fusion starts; expands into a red giant at B; when fusion stops, the core collapses into a white dwarf |
| Jan 26 | Q14(b) | Fusion conditions in a star | Very high core temperature; nuclei gain enough kinetic energy; to overcome electrostatic repulsion; and get close enough to fuse; very high density; collision rate high enough to maintain fusion |
| Oct 25 | Q19(b) | Balloon in hot water: why the pressure rises | Mean kinetic energy rises with temperature; mean speed and momentum rise; more frequent collisions with the balloon; rate of change of momentum rises; force on the balloon rises; p = F/A, so pressure rises and the balloon expands |
| Jun 25 | Q18(b) | The Sun’s evolution | As June 2026. Mean mark only 2 of 6: answers left out “core” and “temperature rises” |
| Jan 25 | Q15 | Millennium Bridge: resonance and dampers | People drive the bridge; resonance when driving frequency = natural frequency; maximum energy transfer; amplitude increases; energy passes to the dampers; dampers dissipate it, limiting the amplitude |
| Oct 24 | Q20(b) | Fusion conditions in a main-sequence star | As January 2026; “very high pressure” accepted for density |
| Jun 24 | Q19(b) | Main sequence → red giant → white dwarf | Hydrogen fusion in the core; core hydrogen runs out; fusion rate falls and the star contracts; temperature rises and helium fusion begins; expands and cools into a red giant; helium fusion stops and it collapses to a white dwarf |
| Jan 24 | Q21(a) | Fusion conditions in a main-sequence star | As January 2026 |
| Oct 23 | Q15 | Calibrating a thermistor from 0 °C to 100 °C | Ohmmeter, or ammeter and voltmeter; thermistor in a water bath; ice to reach 0 °C; heat, measuring temperature with a thermometer; resistance at each temperature; one precaution (stir, thermometer beside the thermistor, wait, small current) |
| Jun 23 | Q18 | Internal energy of cooling wax, times X and Y on a cooling curve | Internal energy decreases; it is the sum of molecular kinetic and potential energies; kinetic energy falls as temperature falls; between X and Y potential energy falls as it solidifies; between X and Y temperature is constant, so kinetic energy is unchanged; at Y it is solid |
| Jan 23 | Q17(b) | Scuba tank warmed in the sun: why the pressure rises | As October 2025, with “change of momentum per collision rises” and “collision rate rises” as separate points |
| Oct 22 | Q13 | Standard candles: the distance to a nearby galaxy | Parallax to a nearby standard candle; measure its intensity; inverse square law gives its luminosity (or a Cepheid’s period–luminosity relation); locate a candle in the galaxy; it has a known luminosity; measure its intensity, inverse square law gives the distance |
| Jun 22 | Q14 | Resonance: a struck glass vs a wet finger | Striking gives free oscillation; energy transferred away, amplitude decays (damped); the finger drives the glass; driving frequency = natural frequency; resonance, maximum energy transfer; amplitude increases |
| Jan 22 | Q19(c)(iii) | A Sun-like star’s evolution across zones of an HR diagram | Hydrogen fusion in the core; fusion ceases and the core contracts; expands into a red giant; core hot enough for helium fusion; helium runs out and fusion ceases; becomes a white dwarf |
| Oct 21 | Q15 | Fusion conditions in stars | As January 2026 |
| Jun 21 | Q18(e) | Detecting alpha radiation by the UV light it causes | Alpha energy transferred to air molecules; electrons excited to higher levels; UV photons emitted as they return; alpha strongly ionising, short range; UV weakly ionising, long range; so detectable safely from further away |
| Jan 21 | Q20(a)(ii) | How a young cluster’s HR diagram changes as it ages | Hydrogen fusion ends and stars become red giants; first for the most massive (top of the main sequence); red giants sit above the main sequence; helium fusion ends and they become white dwarfs; white dwarfs sit below it; red giants larger and cooler, white dwarfs smaller and hotter |
| Oct 20 | Q17(b) | Football: why the pressure falls as the air cools | Mean kinetic energy falls; speed falls; change of momentum per collision falls; collision rate falls; rate of change of momentum (force) falls; p = F/A, so pressure falls |
MCQ analysis
Oscillations supply a quarter of all MCQs (45 of 180), and the same ideas return with the same wrong options. The June 2025 mean was 7 out of 10; the two hardest items that year combined binding energy per nucleon for fission and fusion, and the inverse square law with a background count.
Oscillations supply a quarter of all MCQs
Section A questions per topic across the 18 papers, 180 in all. An even split would be 18 each.
| Recurring idea | Papers | The trap it tests |
|---|---|---|
| Gravity: field ∝ 1/r2, potential ∝ 1/r, orbit speed and GPE changes, weight in orbit, field comparisons | 16 | Field strength ∝ 1/r (Jun 26); zero weight in orbit (Jan 21); gravity able to repel (Jan 25) |
| Redshift, Hubble, age of the universe, critical density, dark matter | 14 | Redshift read as “accelerating away” (Jan 23); H0 left in km s−1 Mpc−1 (Jun 25); dark matter emitting radiation (Jan 21) |
| Gas assumptions, mean kinetic energy ∝ T, rms-speed ratios | 12 | Molecules must be identical (Jun 22, Oct 22); mean kinetic energy depending on the gas, not just T (Jan 21) |
| Damping, plastic deformation, forced and resonant oscillation | 11 | Damping only at resonance (Jun 21); elastic materials as dampers (Jun 23) |
| Wien, Stefan and inverse-square intensity ratios | 11 | Peak at the lower frequency read as the hotter star (Jan 24) |
| HR positions and evolutionary paths | 10 | Impossible paths between regions (Oct 21, Oct 23); how radius, density and temperature change between stages (Jun 24, Jan 25) |
| SHM graphs and phase (x, v, a, Ek, force) | 9 | Acceleration in phase with displacement (Jan 21) |
| Radiation properties and absorption | 9 | Beta as the most ionising, gamma as the least penetrating (Oct 24) |
| Binding energy per nucleon, fission and fusion | 9 | High temperature and density as fission conditions (Jun 26); total binding energy, not per nucleon, peaking at iron-56 (Jan 23) |
| Period scaling (Moon pendulum, T ∝ √m, T ∝ 1/√k) | 7 | Reading half a cycle as the period (Oct 20); √6 the wrong way round (Oct 21) |
| Heating: kinetic vs potential energy at a change of state, latent-heat errors | 7 | Melting raising mean kinetic energy (Oct 20, Jan 24) |
| Background count and its reliability | 6 | Shorter count times (Jan 23); temperature affecting background (Jun 23) |
| Parallax and standard candles | 6 | Parallax largest for distant stars (Jan 24); a candle of known distance rather than luminosity (Oct 21) |
| vmax = ωA, energy ∝ A2 | 6 | Half the amplitude, or f in place of ω (Oct 21) |
| Random vs spontaneous decay | 5 | “We can predict which nucleus decays next” (Jun 26) |
Question-by-question breakdown
Every Section B question in all 18 papers, with what it asks and the method the mark scheme rewards. Part marks are in brackets; the asterisked 6-mark question is labelled.
October 2020 (printed with a June 2020 cover)
MCQs: Q1 radiation identified by absorption in paper, aluminium and lead · Q2 binding-energy graph: light nuclei fusing release energy · Q3 ratio of mean-square speeds of two gases · Q4 NTC thermistor circuit as temperature falls · Q5 pendulum period · Q6 subtracting background with equal count times · Q7 exponential absorption with thickness · Q8 melting: kinetic energy unchanged, potential energy rises · Q9 T ∝ 1/√k · Q10 the term “natural frequency”
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Gravity | One similarity and one difference between electric and gravitational fields |
| 12 | 5 | Doppler | (a) how an orbiting planet shifts its star’s spectral lines: gravitational pull, star’s velocity changes, varying Doppler shift (3); (b) the star’s speed from Δλ/λ = v/c (2) |
| 13 | 4 | Fusion | Why fusion power on Earth is hard: temperature to overcome repulsion, density for collision rate, no container survives |
| 14 | 4 | Luminosity, mass–energy | (a) show LSun ≈ 4 × 1026 W from I = L/4πd2 (2); (b) rate of mass loss from ΔE = c2Δm and P = ΔE/Δt (2) |
| 15 | 7 | Gravity | g–r graph: (a) show g ∝ 1/r2 from readings (3); (b)(i) why mgh fails: g not constant (1); (b)(ii) ΔEgrav from V = −GM/r and mΔV (3) |
| 16 | 8 | Stars | Alnilam and Mintaka: (a) place on the HR diagram (1); (b) λmax by Wien (2); (c) radius by Stefan (2); (d) compare intensities at Earth with I = L/4πd2 (3) |
| 17 | 12 | Gases | Football: (a) deduce whether it meets the rules: circumference → r → V, pV = NkT with °C → K, pressure above atmospheric (6); (b) 6-marker: why the pressure falls as the air cools (6) |
| 18 | 12 | Radioactivity, carry-over | Oganesson: (a) neutrons in the equation (1); (b) name the accelerator (1); speed of the ions from an MeV energy via ½mv2, compared with c (5); (c) N0 from N = N0e^(−λt) (3); (d) two precautions with reasons (2) |
| 19 | 14 | Heating, resonance | Microwave oven: (a) water’s natural frequency from a graph (2); (b) heating by molecular collisions (3), why ice heats slowly (2); (c) efficiency with mcΔθ and P = ΔW/Δt (3); final temperature when ice melts in the water: energy balance with mL and mcΔθ (4) |
| 20 | 12 | Oscillations | Mass on a spring: (a) define SHM (2); (b) k, T, vmax = ωA, maximum kinetic energy (5); (c) sketch kinetic energy against time: twice the frequency, never negative (2); (d) the same system in water: damping by drag (3) |
January 2021
MCQs: Q1 mean kinetic energy set by temperature alone · Q2 dark matter · Q3 alpha ionising, gamma penetrating · Q4 λmax as a metal bar heats · Q5 amplitude ∝ √energy · Q6 I = L/4πd2 ratio · Q7 a satellite’s weight in orbit · Q8 L = 4πr2σT4 · Q9 acceleration in antiphase with displacement · Q10 acceleration as the gradient of velocity–time
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Gravity | Radius of Mars from mass and g ratios (g = GM/r2) |
| 12 | 6 | Heating | 280 W heater: (a) show the time to reach 100 °C with mcΔθ and P = E/t (3); (b) mass boiled away at La Paz (boiling point 87.7 °C) with LΔm (3) |
| 13 | 4 | Carry-over, pendulum | (a) SI base units of energy (1); (b)(i) length of a “seconds pendulum” from T = 2π√(l/g) (2); (b)(ii) why it’s a poor standard: g varies (1) |
| 14 | 5 | Gases | Xenon cylinder: (a) pressure from pV = NkT with °C → K (3); (b) percentage of gas left (2) |
| 15 | 6 | Radioactivity | Gamma absorption by iron: ln graph, μ from the gradient (or the intercept route), half-value thickness (6) |
| 16 | 7 | Cosmology, gravity | (a)(i) define redshift (2); (a)(ii) distance from z = v/c and v = H0d (3); (b) why approaching galaxies accelerate: F ∝ 1/r2, F = ma (2) |
| 17 | 9 | Gravity | Salyut 1: (a)(i) orbital period and orbits per day from the orbit equation (4); (a)(ii) ΔEgrav (3); (b) why it burned up: drag, work done, heating (2) |
| 18 | 13 | Oscillations | Bee’s wings: (a) define SHM (2); (b)(i) amplitude from vmax = ωA (3); (b)(ii) a = −ω2x (2); (c)(i) meaning of “elastic” (1); (c)(ii) resonance (3); (c)(iii) wing frequency a multiple of the muscle frequency (2) |
| 19 | 14 | Radioactivity, mass–energy | Potassium-40: (a)(i) beta-decay equation (2); (a)(ii) decay energy in MeV from the mass difference (5); (a)(iii) why beta energies vary (2); (b) activity from A = λN (3); claim tested with A = A0e^(−λt) (2) |
| 20 | 14 | HR, Doppler, distances | Young cluster: (a)(i) mark the Sun (1); (a)(ii) 6-marker: how the diagram changes as the cluster ages (6); (b)(i) Andromeda’s velocity from a shifted line, approaching (4); (b)(ii) dust lowers intensity so the standard-candle distance comes out too large (3) |
June 2021
MCQs: Q1 background · Q2 meaning of H0 and 1/H0 · Q3 damping happens at all frequencies · Q4 fusion in the Sun · Q5 g ∝ density for equal volumes · Q6 a star like the Sun on the HR diagram · Q7 p ∝ T and mean-square speed · Q8 L ∝ T4 at equal radius · Q9 vmax = 2πA/T · Q10 smaller λmax means hotter
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 6 | Gases | Boyle’s-law apparatus: (a) kinetic explanation of the pressure rise as volume falls (4); (b) pV calculation (2) |
| 12 | 7 | Distances | Fast radio bursts: (a) define a standard candle (1); (b) luminosity from burst energy and duration, then I = L/4πd2 (4); compare with the Sun (2) |
| 13 | 6 | Heating | Chocolate palace: mass from volume and density, mcΔθ + mL, compared with a day’s solar energy (6) |
| 14 | 7 | Oscillations | Pendulum and velocity sensor: (a) sketch displacement from velocity (2); length from T read off the graph (3); (b) when a data logger helps (2) |
| 15 | 8 | Stars, Doppler | (a) T from λmax by Wien (3); (b) recession speed from Δλ/λ = v/c (5) |
| 16 | 9 | Gravity | Starlink: (a) orbital period from the orbit equation (3); (b) why a lower orbit has a shorter period (3); (c) potential difference between orbits (3) |
| 17 | 10 | Oscillations | Spring: (a) define SHM (2); (b)(i) k from ΔF = kΔx (2); (b)(ii) k from the gradient of T2 against m, compared with (i) (6) |
| 18 | 14 | Nuclear energy, radioactivity | (a) define fission (1); (b) sketch the binding-energy-per-nucleon curve and mark iron-56 (3); (c) complete an equation (2); (d) binding energy per nucleon (2); (e) 6-marker: detecting alpha particles by the UV they cause (6) |
| 19 | 13 | Mass–energy, radioactivity | Pu-238 pacemaker: (a) show the decay energy in MeV (5); (b) power from activity × energy per decay (5); (c) beta range from a graph: is 0.5 cm of polyethylene enough? (3) |
October 2021
MCQs: Q1 definition of a standard candle · Q2 electric vs gravitational force between nuclei · Q3 pendulum on the Moon · Q4 gamma for sterilising · Q5 vmax expression · Q6 activity from N and t½ · Q7 energy to split helium-4 · Q8 a possible evolutionary path · Q9 comparing stars on the HR diagram · Q10 period from an a–x graph
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Distances | Distance to Sirius from I = L/4πd2 |
| 12 | 4 | Heating | Kettle: mcΔθ to 100 °C, then the mass boiled away with LΔm |
| 13 | 8 | Mass–energy | Thorium-228: (a) show the decay energy in MeV (4); (b) the alpha’s kinetic energy from momentum and energy conservation (4) |
| 14 | 6 | Gases | (a) show N ≈ 6.0 × 1023 from pV = NkT (3); (b) mass ratio of two molecules from their rms-speed ratio (3) |
| 15 | 6 | Fusion | 6-marker: conditions to start and sustain fusion in stars |
| 16 | 7 | Doppler | The rotating Sun: (a) match three wavelengths to points on the disc (1); (b) why they differ (2); (c) assess a 28-day rotation period with Δλ/λ = v/c and v = 2πr/T (4) |
| 17 | 7 | Distances, cosmology | (a) describe trigonometric parallax (3); (b) how redshifts and distances give H0 and the age of the universe (4) |
| 18 | 8 | Oscillations | Crib on a spring: k (2); why it’s SHM (2); period (2); (b) why the safe load is lower when it oscillates (2) |
| 19 | 9 | Radioactivity | Cobalt-60: equation (2); why most energy goes to the beta and antineutrino (1); (b) activity later with A = A0e^(−λt) (3); (c) is the shielding enough, from a transmission graph (3) |
| 20 | 12 | Stars, gravity | The Sun: (a) define a main-sequence star (1); (b)(i) show r ≈ 7.0 × 108 m with Stefan (2); (b)(ii) red-giant λmax from L ∝ r2T4 and Wien (3); (b)(iii) comment on “red” when λmax is infrared (3); (c) how a planet’s period changes as the Sun loses mass (3) |
| 21 | 11 | Gravity | Polar-orbit satellite: (a)(i) show Vgrav (2); (a)(ii) ΔEgrav (2); (b) assess an orbits-per-day claim with the orbit equation (5); (c) one advantage and one disadvantage of a polar orbit (2) |
January 2022
MCQs: Q1 SHM definition · Q2 latent-heat-of-vaporisation experiment · Q3 pendulum period · Q4 activity halving · Q5 pV ∝ T · Q6 Hubble’s law · Q7 background · Q8 I = L/4πd2 · Q9 redshifted spectral lines · Q10 iron-56 has the highest binding energy per nucleon
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 4 | Oscillations | Spring with an a–x graph: ω from a = −ω2x, then the period and a displacement–time sketch |
| 12 | 5 | Heating | Hot chocolate and ice at 0 °C: deduce whether it reaches the safe temperature by energy balance (mL + mcΔθ) |
| 13 | 5 | Gases | Weather balloon: (a) new volume from pV/T (3); (b) change in mean kinetic energy from ½m⟨c2⟩ = 3/2 kT (2) |
| 14 | 5 | Radioactivity | Strontium-90 betas: range in air from energy per ion pair and ion pairs per cm, using an energy graph |
| 15 | 5 | Stars | Procyon: assess “twice the Sun’s diameter” with λmax from a graph, Wien, then Stefan |
| 16 | 7 | Cosmology | Galaxy rotation: (a) orbital speed from GMm/r2 = mv2/r for outer stars (3); (b) dark matter (2); (c) density vs critical density (2) |
| 17 | 9 | Oscillations, carry-over | Loudspeaker: (a) force on the coil in a magnetic field (3); (b) cone’s vmax = ωA (3); (c) equilibrium position (1); (d) resonance (2) |
| 18 | 8 | Gravity | Kepler’s “law of harmonies”: (a) calculate K (3); (b) derive K = 4π2/GM (3); (c) a moon’s period (2) |
| 19 | 18 | Distances, HR | Cepheids: (a) furthest distance from the smallest parallax angle (3); (b) standard candles (3); (c)(i) HR axis scales (3); (c)(ii) zones on the diagram (3); (c)(iii) 6-marker: a Sun-like star’s evolution across the zones (6) |
| 20 | 14 | Radioactivity, mass–energy | Actinium-225: (a) equation (2); (b) show 1 u ≈ 934 MeV (4); (c) why the alpha takes most of the kinetic energy (4); (d) N = N0e^(−λt) (4) |
June 2022
MCQs: Q1 HR log scale · Q2 maximum acceleration in SHM · Q3 which quantity’s unit differs (decay constant, angular velocity, frequency) · Q4 F = GMm/r2 · Q5 fusion conditions · Q6 g with M = ρ × 4/3 πr3 · Q7 mean momentum of gas molecules is zero · Q8 molecules needn’t be identical · Q9 N–t decay graph · Q10 velocity from a displacement–time graph
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | Distances | Distance to galaxy M81 from a standard candle’s L and I (I = L/4πd2) |
| 12 | 6 | Cosmology | (a) show 72 km s−1 Mpc−1 ≈ 2.3 × 10−18 s−1 (2); age of the universe from 1/H0 (2); (b) effect of a halved H0 (2) |
| 13 | 7 | Radioactivity | Potassium-40: (a) β− equation (2); (b) two similarities of β− and β+ (2); (c) A = A0e^(−λt) (3) |
| 14 | 6 | Oscillations | 6-marker: resonance, a struck glass vs a wet finger |
| 15 | 7 | Mass–energy | Polonium-210: (a) show the energy released (3); alpha speed from ½mv2 with 98% of the energy (2); (b) the lead nucleus recoils, momentum conserved (2) |
| 16 | 11 | Gravity | (a)(i) show T2 ∝ r3 (3); (a)(ii) time between planetary alignments (5); (b) ΔEgrav (3) |
| 17 | 10 | Oscillations | Diving board: SHM conditions (2); k (2); frequency (3); when the diver loses contact (3) |
| 18 | 10 | Distances, stars | Wolf 359: (a) distance from a parallax angle (2) and the parallax limit (2); (b) temperature by Wien (3); (c) Stefan (3) |
| 19 | 8 | Gases, Doppler, HR | Chi Lupi: (a) mercury lamp, kinetic theory (3); (b) Doppler speed (4); (c) place on the HR diagram (1) |
| 20 | 12 | Heating, carry-over | Lead shot tower: (a) time of fall (2); (b) mass from density, mcΔθ, latent heat and power (6); (c) why Δθ doesn’t depend on mass (2); (d) evaluate accuracy (2) |
October 2022
MCQs: Q1 fission and fusion both raise binding energy per nucleon · Q2 which condition isn’t needed for the gas laws (identical molecules) · Q3 radiation identified by absorbers · Q4 HR temperature-scale values · Q5 random and spontaneous decay · Q6 gradient of z against d is H0/c · Q7 ΔEgrav from R to 2R · Q8 pendulum length l = T2g/4π2 · Q9 luminosity ratio from I = L/4πd2 · Q10 effect on amplitude and natural frequency
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 5 | Heating | Bath vs shower: flow rate and density for the shower’s mass, mcΔθ, test the “10 times” claim |
| 12 | 5 | Gases | Density of oxygen in a cylinder: pV = NkT with °C → K, mass = N × mass of a molecule, ρ = m/V |
| 13 | 6 | Distances | 6-marker: how a standard candle’s luminosity is found and used to measure distances to galaxies |
| 14 | 6 | Oscillations | Bay of Fundy tides: (a) period from a 7-day graph over several cycles (3); (b) why the tides are so large: resonance (3) |
| 15 | 7 | Cosmology | GN-z11: (a) observed wavelength from z (2); (b) distance from a graph and s = ct (3); (c) why it’s observed in the infrared (2) |
| 16 | 8 | Stars | Gliese-876: (a) show T ≈ 3000 K from a peak frequency, λ = c/f, then Wien (4); (b) luminosity compared with the Sun’s using Stefan (4) |
| 17 | 9 | Gravity | Ceres: (a) show the Sun’s pull ≈ 7 × 1017 N (2); orbital period in years (4); (b) its surface g compared with Mercury’s (3) |
| 18 | 9 | Mass–energy, radioactivity | Joliot-Curie: (a) identify a neutron (1); energy from the mass difference (4); (b) PET: positron annihilation, gamma escapes the body, half-life suitability (4) |
| 19 | 11 | Oscillations | Paint shaker: (a) SHM conditions (2); (b) period from oscillations per minute, sketch (6); a = −ω2x (2); (c) why the paint mixes (1) |
| 20 | 14 | Radioactivity | Caesium-137: (a) define fission (1); (b) equation (2) and recoil (2); (c) activity from a mass via A = λN (6); time for the activity to fall to a safe level (3) |
January 2023
MCQs: Q1 making a background count more reliable · Q2 mean kinetic energy depends only on temperature · Q3 iron-56 and binding energy per nucleon · Q4 latent heat L = Pt/m · Q5 redshift means moving away · Q6 mass from an energy in MeV · Q7 half-thickness · Q8 a cluster with white dwarfs but no red giants · Q9 vmax = 2πx0/T · Q10 acceleration–time from a gradient
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 4 | Heating | Swimming pool: (a) ΔE with mass from ρV and mcΔθ (3); (b) why more energy is needed in practice (1) |
| 12 | 6 | Gravity, gases | Escape velocity: (a) show v = √(2GM/r) (2); (b) Earth’s value (2); why some gas escapes anyway: a spread of molecular speeds (2) |
| 13 | 5 | Cosmology | M87: assess “55 million light-years” with z = Δλ/λ, v = H0d and a light-year conversion |
| 14 | 5 | Oscillations | Elastic potential energy graph: (a) total-energy line (1); (b) speed at a displacement from energies read off the graph (4) |
| 15 | 6 | Radioactivity | Caesium-137: (a) equation (2); (b) sample mass from activity: λ, dN/dt = −λN, u (4) |
| 16 | 7 | Cosmology, mass–energy | Dark matter as a neutrino: (a) describe dark matter (2); (b) neutrino mass from an eV energy, ΔE = c2Δm (3); (c) why the universe’s fate is uncertain (2) |
| 17 | 10 | Gases | Scuba tank: (a) pressure change when warmed, p/T constant (4); (b) 6-marker: why the pressure rises (6) |
| 18 | 9 | Distances | Tycho Brahe: (a) describe stellar parallax (4) and why he couldn’t detect it (1); (b) define a standard candle (1) and describe the method (3) |
| 19 | 9 | Oscillations | Car over speed bumps: (a) resonance (2); (b) the resonant speed from k, f and the bump spacing (5); (c) dampers dissipate energy (2) |
| 20 | 8 | Gravity, carry-over | Cavendish: (a) is the force between lead spheres measurable? r = R1 + R2, F = Gm1m2/r2 (4); (b) base units of G (2); percentage difference (2) |
| 21 | 11 | Stars, gravity | Kapteyn-b: (a) T by Wien (2); intensity at the planet vs Earth with Stefan and I = L/4πd2 (4); (b) the planet’s g from density and 4/3 πr3 (5) |
June 2023
MCQs: Q1 average density below critical · Q2 observed wavelength λ + 0.025λ · Q3 distance from a parallax angle · Q4 change in GPE between radii · Q5 v = H0d · Q6 best damper: large plastic deformation · Q7 what doesn’t affect background (temperature) · Q8 g on Mars · Q9 same temperature, same mean kinetic energy · Q10 acceleration from velocity–time
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 5 | Radioactivity | Rhenium-187: (a) β− equation (2); (b) the beta’s speed from 2.6 keV: eV → J, ½mv2 (3) |
| 12 | 5 | Gases | Airbag: (a) show N ≈ 2 × 1024 from pV = NkT (3); (b) extra molecules needed (2) |
| 13 | 4 | Radioactivity | Cloud chamber: thick, straight alpha tracks vs thin, twisted beta tracks (ionising ability, mass) |
| 14 | 7 | Heating | Ice cube tray: (a) mass from dimensions and density (3); (b) energy to cool and freeze it: mcΔθ + mL (4) |
| 15 | 6 | Oscillations | A baby’s heart: (a) amplitude from vmax and beats per minute (4); (b) SHM conditions (2) |
| 16 | 8 | Mass–energy, radioactivity | Thorium-230: (a) energy from the mass difference (4); (b) time for 90% to decay (4) |
| 17 | 9 | Fusion | (a) why fusing hydrogen releases energy (2); (b) the conditions for fusion (4); (c) energy from the binding-energy-per-nucleon graph (3) |
| 18 | 6 | Heating | 6-marker: the internal energy of cooling wax, times X and Y on a cooling curve |
| 19 | 10 | Oscillations | (a) check a spring label from timing 30 oscillations, T = 2π√(m/k) (4); (b)(i) resonance (3); (b)(ii) energy transfer at maximum amplitude, a claim (3) |
| 20 | 9 | HR, distances | (a) add a temperature scale (2); (b) why the cluster isn’t young (3); (c) distance by a standard candle (4) |
| 21 | 11 | Stars, gravity | Ross-154: (a) show T ≈ 3000 K (3); luminosity claim with Stefan (5); (b) a planet’s orbital period (3) |
October 2023
MCQs: Q1 fusion conditions · Q2 parallax · Q3 iron-56 · Q4 the damping force opposes velocity · Q5 wavelength from a receding source · Q6 gravitational potential vs force · Q7 g at 2R is g/4 · Q8 ionising vs penetrating · Q9 evolutionary path · Q10 T = 2π√(l/g)
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | Gases | Average kinetic energy of air in a balloon, from pV = NkT and ½m⟨c2⟩ = 3/2 kT |
| 12 | 4 | Gases | p–V graph: test Boyle’s law by working out pV at three points |
| 13 | 6 | Mass–energy | Rutherford’s transmutation: (a) minimum energy in MeV, products heavier (4); (b) why more is needed: momentum conservation (2) |
| 14 | 4 | Cosmology | (a) how we know galaxies recede (1); (b) assess Hubble’s law from his scattered data (3) |
| 15 | 6 | Practical | 6-marker: calibrating a thermistor from 0 °C to 100 °C, with one precaution |
| 16 | 7 | Heating | Kettle: (a) power from mcΔθ and time (4); (b) time to boil water away with latent heat (3) |
| 17 | 8 | Gravity | Makemake: (a) surface g (2); (b) orbital period from the orbit equation (6) |
| 18 | 9 | Gravity | Asteroid: (a) force from its density and diameter (4); (b) ΔEgrav (3); (c) why it burns up (2) |
| 19 | 10 | Radioactivity | Caesium-137 source: (a) show λ (2); mass from activity (3); (b) activity later (2); (c) energy released over a period (3) |
| 20 | 10 | Oscillations | (a) why the motion is SHM (2); (b) maximum velocity (6); (c) damping and energy transfer (2) |
| 21 | 13 | Stars, HR, Doppler | Betelgeuse: (a)(i) assess “radius 1000 × the Sun’s” with Wien and Stefan (4); (ii) plot positions on the HR diagram (2); (iii) define a main-sequence star (1); (b) rotating neutron star: maximum and minimum observed wavelengths from v = 2πr/T and Δλ/λ = v/c (6) |
January 2024
MCQs: Q1 ice melting: kinetic energy unchanged, potential energy up · Q2 parallax facts · Q3 mass–energy equivalence · Q4 SHM acceleration always towards equilibrium · Q5 meaning of “spontaneous” · Q6 Mercury nearing the Sun: GPE down, speed up · Q7 vmax = ωA · Q8 mean-square speeds of helium vs hydrogen · Q9 the hotter star from peak frequency · Q10 g = GM/r2
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | HR | Evolutionary path from area P: massive main sequence → red giants (S) → white dwarfs (Q) |
| 12 | 4 | Oscillations, gravity | Pendulum on Venus: length from its Earth period, g = GM/r2 for Venus, new period |
| 13 | 3 | Doppler | A galaxy’s spectral line at a lower frequency: speed (or z) and direction |
| 14 | 5 | Gases | Racing-bike tyre: N from the mass of a molecule, pV = NkT with °C → K, pressure difference |
| 15 | 5 | Heating | Banana in liquid nitrogen: (a) why the nitrogen boils (2); (b) is 0.5 kg enough? mcΔθ vs mL, compare (3) |
| 16 | 8 | Stars, gravity | Pluto: (a) intensity of sunlight at Pluto from Stefan and I = L/4πd2 (4); (b) its orbital period in years (4) |
| 17 | 7 | Gravity, oscillations | Skylab: (a) why astronauts seem “weightless” (2); (b) an astronaut’s mass from k and the chair’s periods (5) |
| 18 | 11 | Stars, distances, cosmology | Kruger 60: (a) assess “TA = 2TB” with Wien (3); (b) the standard-candle method (4); (c) age of the universe from v and d (4) |
| 19 | 13 | Fission, radioactivity | (a) why fission releases energy (2); (b) energy from the binding-energy-per-nucleon graph (3); (c) strontium-90 equation (2), total energy released (3), decay constant (3) |
| 20 | 9 | Radioactivity | (a) identify the radiation from counts with paper and aluminium (4); (b) μ from a ln graph’s gradient, then identify the source from a table (5) |
| 21 | 12 | Fusion | (a) 6-marker: conditions for fusion in a main-sequence star (6); (b) binding energy per nucleon of helium (4); why helium is so stable (2) |
June 2024
MCQs: Q1 main sequence → white dwarf: density and surface temperature both rise · Q2 trigonometric parallax · Q3 double amplitude, 4 × energy · Q4 forced oscillation at the driving frequency · Q5 decay can’t be predicted · Q6 higher orbit: force and speed both lower · Q7 red dwarf · Q8 rms-speed ratio for twice the molecular mass · Q9 SHM acceleration–time graph · Q10 SHM displacement–time graph
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Gravity | Why equipotential surfaces aren’t equally spaced |
| 12 | 3 | Gravity | A vehicle’s weight on Titania, g = GM/r2 |
| 13 | 6 | Gases, carry-over | Airship: (a) why it floats: upthrust = weight (2); (b) mass of helium from pV = NkT and the mass of an atom (4) |
| 14 | 6 | Radioactivity | (a) why alpha can’t pass through lead (1); (b) background and repeat counts (2); (c) μ from R = R0e^(−μx) or a tangent (3) |
| 15 | 9 | Heating | Ice floe: (a) show the melting energy: mcΔθ + mL (3); (b) days to melt from solar intensity at sea level, area and power (6) |
| 16 | 8 | Stars, Doppler | ε-Eridani: (a) λmax from intensity at Earth → L → T → Wien (5); (b) can a spectrometer resolve the Doppler shift? (3) |
| 17 | 10 | Radioactivity | Iodine-131: (a) equation (2); (b) mass needed for an activity: λ, A = λN, M = N × m (6); activity 24 h earlier (2) |
| 18 | 9 | Gravity, dark matter | (a) derive the orbital-period expression (3); (b) a star’s period from the galaxy’s mass (2); the real period is shorter, so there’s dark matter (4) |
| 19 | 15 | Fusion, HR | (a) energy when 4 protons form helium (4); assess a claim about the Sun’s hydrogen use (5); (b) 6-marker: main sequence → red giant → white dwarf (6) |
| 20 | 12 | Oscillations | Building damper (lead box): (a) SHM conditions (2); (b) match natural frequency for maximum energy transfer (2); k from T and the box’s mass (4); why the box is heavily damped (2); (c) work done forcing oil through holes (2) |
October 2024
MCQs: Q1 alpha is the most ionising · Q2 ductile materials absorb energy by plastic deformation · Q3 what an intensity–wavelength graph shows (temperature) · Q4 a ∝ −x · Q5 ΔEgrav = mΔV · Q6 T = 2π√(m/k) and frequency · Q7 density, critical density and the universe’s fate · Q8 a main-sequence star’s T and L · Q9 force in antiphase with displacement · Q10 SHM velocity–time graph
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Gases | Internal energy of helium, 3/2 NkT |
| 12 | 4 | Heating | Molten bronze: final temperature by energy balance, including the latent heat of tin |
| 13 | 5 | Oscillations | Two pendulums: assess a claim about maximum kinetic energy via T, ω, vmax = ωA |
| 14 | 5 | Gases | Methane bubble: diameter at the surface from p1V1/T1 = p2V2/T2, with pressure at depth |
| 15 | 7 | Stars, distances | Sirius and Canopus: (a) Sirius’s luminosity by Stefan (3); (b) assess “twice as bright” with I = L/4πd2 (4) |
| 16 | 6 | Practical | Describe calibrating a thermistor from 0 °C to 100 °C, with any extra equipment (point-marked) |
| 17 | 8 | Doppler, cosmology | Arcturus: (a) why its spectrum is shifted (2); its speed (3); (b) how distances to distant galaxies are found from redshift (3) |
| 18 | 8 | Gravity | Galileo and Ganymede: (a) deduce whether 8 days was enough to see an orbit (4); (b) show g on Ganymede (2); compare with the Moon (2) |
| 19 | 9 | Oscillations | Spring balance: (a) show k ≈ 45 N m−1 (3); frequency of oscillation (4); (b) explain the large oscillation: resonance (2) |
| 20 | 13 | Stars, HR, fusion | (a) the Sun’s T from a peak frequency, λ = c/f then Wien (3); mark the Sun (1); label areas A, B, C (3); (b) 6-marker: fusion conditions (6) |
| 21 | 13 | Radioactivity, binding energy | Uranium-241: (a) β− equation (2); show its binding energy ≈ 3 × 10−10 J (5); binding energy per nucleon in MeV (2); (b) deduce a ratio of nuclei after a time (4) |
January 2025
MCQs: Q1 red giant: diameter up, surface temperature down · Q2 materials that deform plastically as dampers · Q3 which field statement is false (both can repel) · Q4 stability from binding energy per nucleon · Q5 parallax baseline is the Earth–Sun distance · Q6 mass ratio from rms speeds · Q7 age of the universe with a new H0 · Q8 less damping: amplitude decays more slowly · Q9 Earth–Moon gravitational force · Q10 temperature–time graph and specific heat capacities
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | Oscillations | Added mass from two periods, T = 2π√(m/k) |
| 12 | 3 | Gravity | Show MEarth ≈ 6 × 1024 kg from a V–r graph |
| 13 | 6 | Heating | Hot plate: (a) efficiency from the water boiled away, LΔm and P (4); (b) why a lid helps (2) |
| 14 | 6 | Gravity | (a) show MSun ≈ 2 × 1030 kg from the Earth’s orbit (3); (b) assess “g at the Sun’s surface is 28 × Earth’s” (3) |
| 15 | 6 | Oscillations | 6-marker: Millennium Bridge, resonance and dampers |
| 16 | 7 | Distances | (a) define a standard candle (1); (b) a Cepheid’s luminosity from the period–luminosity graph (4); its distance from I = L/4πd2 (2) |
| 17 | 9 | Oscillations | a–x graph: (a) why it’s SHM (2); (b) maximum kinetic energy via ω from the gradient (5); sketch kinetic energy against x (2) |
| 18 | 8 | Stars, Doppler | (a) why absorption happens only at certain wavelengths: discrete energy levels (3); (b) the rotating Sun: assess a statement about the Doppler shift at its edges (5) |
| 19 | 10 | Gases, stars | Argon-filled bulb: (a) N at 75% of atmospheric pressure (3); (b) assess a temperature statement (3); (c) filament power from Wien and Stefan (3); why it differs: not a perfect black body (1) |
| 20 | 10 | Heating | Boiling-water tap: (a) energy to heat water to 110 °C (5); (b) energy used by a kettle vs the tank, conclude (5) |
| 21 | 12 | Radioactivity, binding energy | (a) why beta suits a paper-thickness gauge (2); Pm-147 equation (2); time for the activity to fall to 0.75% (4); (b) binding energy per nucleon (4) |
June 2025
MCQs: Q1 field strength ∝ 1/r2 for both fields · Q2 frequency of a forced oscillation · Q3 binding energy per nucleon rises in fission and fusion · Q4 age from H0 in km s−1 Mpc−1 · Q5 wavelength from a source receding at 0.1c · Q6 count rate at a new distance with background · Q7 intensity after absorbers · Q8 which star is hotter and closer, from a graph · Q9 SHM velocity–time graph · Q10 SHM acceleration–time graph
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | Oscillations | Bungee jumper: period with the combined mass |
| 12 | 4 | Radioactivity | Cloud chamber: criticise a student’s statement about the tracks |
| 13 | 7 | Gravity | Satellite: (a) ΔEgrav from the surface to orbit (3); (b) deduce whether its orbit is geostationary (4) |
| 14 | 6 | Distances | (a) why parallax only works for nearby stars (2); (b) define a standard candle (1) and describe the method (3) |
| 15 | 8 | Oscillations | Racing-car suspension: (a) SHM conditions (2); (b) vmax from a graph (4); (c) energy in the dampers: work against resistive forces (2) |
| 16 | 7 | Heating | Ice packs: (a) energy to freeze and cool the block (5); (b) how the ice keeps food cold: energy flows from food to ice (2) |
| 17 | 9 | Gases, gravity | Gaia globe: (a) mass of nitrogen from pV = NkT with 4/3 πr3 (5); (b) rotation time from ω (2); (c) mass of a sphere giving g = 9.8 N kg−1 (2) |
| 18 | 11 | HR | (a) mark the Sun and draw its path to red giant then white dwarf (3); (b) 6-marker: the Sun’s evolution (6); (c) why massive stars leave the main sequence sooner (2) |
| 19 | 10 | Stars, gases | Tau Ceti: (a) show T ≈ 5300 K from a peak frequency (3); mean kinetic energy of surface atoms (2); (b) assess the intensity at a planet against 1360 W m−2 (5) |
| 20 | 15 | Radioactivity, mass–energy | Galileo probe, Pu-238: (a) equation (2); (b) show the decay energy in MeV (4); activity and power output (5); power after 74 months (2); (c) why solar cells won’t work near Jupiter: inverse square law (2) |
October 2025
MCQs: Q1 resonance: pushing a swing at the same point each cycle · Q2 alpha and gamma ionisation and penetration · Q3 damping force opposes velocity · Q4 H0 from the age of the universe · Q5 the term “damped” · Q6 a star half as far away · Q7 intensity spectra of two stars · Q8 force and GPE through the Earth’s orbit · Q9 period ratio for half the mass · Q10 rms-speed ratio for argon
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Gravity | g on Proxima Centauri b, radius 40% larger than Earth’s |
| 12 | 2 | Doppler | Andromeda’s speed from a frequency shift |
| 13 | 4 | Gravity | (a) derive escape velocity from kinetic energy = GPE (2); (b) the radius at which it equals c (2) |
| 14 | 5 | Gases | Balloon in hot water: deduce whether the air reaches the water’s temperature, V/T from the diameters |
| 15 | 8 | Oscillations | Test tube bobbing in water: meaning of x and the force’s direction (2); maximum kinetic energy (4); (b) sketch velocity from the acceleration graph (2) |
| 16 | 6 | Heating | Mugs: (a) final temperature by energy balance, compared with 65 °C (4); (b) effect on the colour-change time (2) |
| 17 | 8 | Radioactivity | (a) strontium-90 equation (2); (b) caesium-137 atoms from activity (3); assess a suggestion with A = A0e^(−λt) (3) |
| 18 | 11 | HR, stars | (a) scale and label the temperature axis (2); why the cluster is old (2); (b) Arcturus’s radius from Wien and Stefan, assess (5); its position relative to the Sun (2) |
| 19 | 10 | Carry-over, gases | Party balloon: (a) why it accelerates upwards: upthrust exceeds weight (4); (b) 6-marker: why the pressure rises with temperature (6) |
| 20 | 11 | Binding energy | (a) why uranium-235 fission releases energy but helium-4 wouldn’t (3); (b) show iron-56’s binding energy per nucleon ≈ 9 MeV (6); uranium-235’s value from the graph (2) |
| 21 | 13 | Distances, HR, gravity | (a) describe parallax (3); (b) two properties of a white dwarf (2); Type 1a supernovae as standard candles (3); (c) height of a geostationary satellite (4); lasers on the Moon as known sources (1) |
January 2026
MCQs: Q1 subtract background · Q2 significant plastic deformation (damper) · Q3 unit of intensity · Q4 distance ratio from intensity · Q5 density below critical: expands forever · Q6 decay can’t be influenced (spontaneous) · Q7 intensity ratio of two standard candles · Q8 count rate after decay, with background · Q9 order of spectral classes by temperature · Q10 latent-heat experiment error
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 2 | Doppler | A nearby galaxy’s speed from a shifted hydrogen line |
| 12 | 2 | Heating | Energy change when two solutions mix, mcΔθ |
| 13 | 4 | Gases | Airbag volume: N from the mass of nitrogen, pV = NkT with °C → K |
| 14 | 9 | Nuclear energy | (a) why uranium fission releases far more energy than fusing two hydrogen nuclei (3); (b) 6-marker: fusion conditions (6) |
| 15 | 6 | Oscillations | Pendulum: (a) show T ≈ 1.6 s (2); (b) maximum kinetic energy from the amplitude (4) |
| 16 | 6 | Heating | Salt pans: water evaporated using L read from a graph, against the energy from burning coal, deduce |
| 17 | 11 | Cosmology, gravity | (a) state what dark matter is (2); (b) ISS orbits per day (5); (c) evaluate the claim that astronauts have no weight (4) |
| 18 | 14 | Stars, gravity, gases | Trappist-1: (a) is it a typical red dwarf? radius from Stefan (4); show λmax ≈ 1.1 × 10−6 m (2); why it still gives some red light (2); (b) g on a planet (2); mean kinetic energy of the atmosphere (2); effect of a higher temperature (2) |
| 19 | 15 | Mass–energy, radioactivity | Polonium-214: (a) decay energy in MeV (5); why the alpha’s maximum energy is less: the lead recoils (2); (b) lead-210 equation (2); deduce whether a textbook figure is right with A = A0e^(−λt) (4); (c) why radon is a hazard (2) |
| 20 | 11 | Gravity, carry-over | Mars landing: (a) Mars’s mass from a V–r graph (3); ΔEgrav from potentials (3); why a parachute reduces damage: momentum and impact force (4); (b) why the parachute must be larger on Mars (1) |
June 2026
MCQs: Q1 fission: total mass decreases · Q2 “we can predict which nucleus decays next” is false · Q3 alpha-decay energy (mX − mY − mα)c2 · Q4 galaxies ordered by redshift · Q5 SHM kinetic energy against displacement · Q6 weight on a planet · Q7 electric vs gravitational field of a proton · Q8 GPE change for a 2000 m launch · Q9 latent-heat error: heater on for longer than t · Q10 luminosity from radius and temperature ratios
| Q | Marks | Topic | What is asked, and the method rewarded |
|---|---|---|---|
| 11 | 3 | Gases | Sealed cylinder warmed from 18 °C to 32 °C: new pressure, p/T constant |
| 12 | 6 | Heating | Engine coolant: (a) rate of energy transfer from flow rate and mcΔθ (3); (b) why water would be better: larger c (3) |
| 13 | 5 | Gases | (a) derive U = 3/2 pV (2); (b) mean kinetic energy of a molecule (3) |
| 14 | 4 | Heating | Ice cream: energy to freeze its ice content, ρV, 32%, mL |
| 15 | 4 | Doppler | Gatso speed camera: speed from Δf/f = v/c, then deduce whether it’s over the 10% margin |
| 16 | 8 | HR | (a) temperature axis: reversed and logarithmic (2); (b) 6-marker: the Sun’s evolution, positions A and B (6) |
| 17 | 6 | Distances, cosmology | (a) deduce whether parallax can reach the Blaze Star (3); (b) how distances to the most distant galaxies are found (3) |
| 18 | 7 | Radioactivity | Torbernite: (a) deduce whether the sample is typical: A = λN, u, 65% uranium (5); (b) why it’s safe to handle: alpha has a short range (2) |
| 19 | 11 | Fusion, radioactivity | (a) conditions for fusion (4); (b) tritium beta equation (2); deduce with A = λN or N = N0e^(−λt) (5) |
| 20 | 13 | Oscillations | Carriage on springs: (a) SHM conditions (2); (b) k (2) and frequency (3); (c) resonance (3); how to reduce the amplitude: add damping (3) |
| 21 | 13 | Gravity, stars | (a) Venus’s orbital period from the Earth’s (3); effect of the Sun’s mass loss on the Earth’s orbit (2); (b) show the Sun’s T ≈ 6000 K by Wien (3); the Sun’s radius from the intensity reaching the ground (25%) (5) |
Where candidates lose marks
The June 2025 WPH15 examiners’ report shows marks lost on wording and set-up more than on physics: missing conclusions, missing “equilibrium position”, undefined symbols, and the wrong area or radius.
| Question type | What went wrong | How common (June 2025) |
|---|---|---|
| Sun’s evolution (6-marker) | Left out “core”, “fusion rate decreases”, “temperature rises” before helium fusion, and the core contracting to a white dwarf | Mean 2 of 6 |
| Solar cells near Jupiter | No mention of the inverse square law | About three quarters scored 0 |
| Massive stars’ lifetimes | Didn’t link higher core temperature to a faster fusion rate | About half scored 0 |
| Power from a radioactive source | Didn’t connect power = activity × energy per decay | Seen only in the best answers |
| Cloud-chamber tracks | Compared alpha and beta instead of linking each feature to its cause; no critique of the statement | Mean 2 of 4 |
| Ice pack explanation | Thought the ice gives out “cold” or melts using its own energy | Mean 1 of 2 |
| ΔEgrav to an orbit | Added the Earth’s radius to an orbit radius; forgot to multiply by mass; used mgh (no credit) | About a third scored full marks |
| Is the orbit geostationary? | No comparison of values in the conclusion; Kepler’s law earns no “use of” credit | Under a third scored full marks |
| Standard-candle method | Described a candle as a method; skipped “locate a candle”; equation without symbols defined; “observed” for “measured” | About a third scored full marks |
| SHM definition | “Displacement” without “from the equilibrium position” | Commonly 1 of 2 |
| Parallax limit | “Angle too small” or “hard to measure” instead of resolution or percentage uncertainty | The second mark was rare |
| Damping in a suspension | Resistive forces not linked to work done; work done “on” vs “by” confused; resonance mentioned | About half scored the first mark |
| vmax from a graph | Didn’t set sin ωt = 1 | Common error |
| Energy for an ice block | Lengths not in m; c and L swapped; energies subtracted instead of added | Two thirds scored full marks |
| Gas mass in a sphere | 4/3 πr3 not known; radius halved when it was already a radius; °C not converted | Three quarters scored full marks |
| Intensity at a planet | Area of a circle or volume used instead of 4πr2; no comparison with the given value | Common error |
| Wien “show that” | Frequency substituted for wavelength; missing unit or significant figure | Common error |
| MCQs | Binding energy per nucleon in fission and fusion; inverse square law with a background count | Facility below 0.6 |
Predictions for October 2026
The best bet for the 6-marker is fusion conditions, with kinetic-theory pressure close behind: together they filled 4 of the 6 October slots. Nine methods are near-certain in Section B, each having appeared in 15 to 18 of the 18 papers.
The 6-mark question, ranked
| Rank | Topic | For | Against |
|---|---|---|---|
| 1 | Fusion conditions in a star | 4 of 18 overall, including Oct 21 and Oct 24. 2026 has so far followed 2024 exactly: fusion in January, the Sun’s evolution in June, then fusion in October 2024 | Already tested in Jan 26 (6 marks) and Jun 26 (4 marks) |
| 2 | Gas pressure explained by kinetic theory | 3 of 18, two of them in October (2020, 2025) | It would repeat last October’s topic |
| 3 | Resonance and damping | Last a 6-marker in Jan 25; resonance or damping appeared in short form in 13 of 18 papers | June 2026 already gave it 6 marks across Q20(c) |
| 4 | A thermal or practical “describe”: thermistor calibration, internal energy on a cooling curve, or another Unit 5 core practical | Practical methods have favoured October (Oct 23 6-marker, Oct 24 6-mark method) | The thermistor has been used twice already |
| 5 | The Sun’s evolution | The most frequent 6-marker (5 of 18) | All five were January or June papers, the latest in Jun 26 |
| 6 | Standard candles and the distance ladder | Oct 22; the method had no structured question in either 2026 paper | Only once as a 6-marker |
Near-certain in Section B
| Method | Papers so far |
|---|---|
| pV = NkT with °C → K | 18 of 18 |
| Decay maths: λ = ln 2/t½ with A = λN or N = N0e^(−λt) | 18 of 18 |
| mcΔθ, usually with LΔm | 18 of 18 (latent heat 15 of 18) |
| Wien, usually with Stefan | 17 of 18 (Stefan 16 of 18) |
| Mass difference → energy in MeV | 17 of 18 |
| Completing a nuclear equation | 17 of 18 |
| Orbit equation for T, r or M | 16 of 18 |
| Doppler shift for a speed | 15 of 18 |
| SHM period from 2π√(m/k) or 2π√(l/g) | 15 of 18 |
Likely to return after a gap
- The standard-candle method or definition: a structured question in 11 of the 16 papers up to Oct 25, but neither 2026 paper had one.
- A binding-energy-per-nucleon calculation: in 5 papers, none in 2026.
- Gamma absorption and μ (core practical 15): no structured question since Jun 24.
- An energy-balance mixture (hot and cold, or ice melting): three of its four appearances were October papers (2020, 2024, 2025).
- ΔEgrav between two radii: in 12 of 18 papers, but only an MCQ in Jun 26.
October papers specifically
- Topic weights in the six October papers match the overall averages to within about 1.5 marks per topic, with slightly more gases and gravity and slightly less radioactivity and HR.
- Four of the last five October papers had 11 structured questions, and October 2025 opened Section B with two 2-mark questions.
- Expect the A boundary somewhere between 54 and 71; a candidate scoring 72 or more on recent timed papers is in a safe position.
These predictions come from patterns in past papers only. Every topic scored marks in every paper, so the whole specification still needs covering.