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A-Level Physics Paper 3 Drilling: Measurement, Uncertainty and Graph Gradients
TUTORZONE ORIGINAL DRILLING MOCK · CAMBRIDGE A-LEVEL PHYSICS 9702 PAPER 3
Written to the Cambridge 9702 syllabus (2025-2027): Paper 3 Advanced Practical Skills, 40 marks, 2 hours (practical work and structured questions, 23% of AS and 11.5% of the A Level). Six parts for 40 marks: instrument precision, an R-L gradient, resistivity, combining uncertainties and the area under a force-extension curve, with answers and technique. Questions and answers are original, not Cambridge past-paper material.
What is in A-Level Physics 9702 Paper 3?
Direct answer: Paper 3 Advanced Practical Skills, 40 marks in 2 hours, practical work plus structured questions, 23% of the AS Level and 11.5% of the A Level. The context may lie outside the syllabus content; the marks are for measuring, recording, uncertainty and graph analysis.
Assessment at a glance (2027)
| Component | Content | Weighting | Duration |
|---|---|---|---|
| Paper 3 (Advanced Practical Skills) | Practical work and structured questions, 40 marks | AS 23%／A Level 11.5% | 2 hours |
| Paper 2 (AS structured) | Structured questions, 60 marks | AS 46%／A Level 23% | 1 h 15 min |
| Paper 4 (A Level structured) | Structured questions, 100 marks | A Level 38.5% | 2 hours |
Paper 3 technique: name the instrument and its precision first, then the readings and the uncertainty, and only then the result. Percentage uncertainty = error / reading x 100%; the area factor (pi d^2 / 4) doubles the diameter uncertainty. Split a curve into a triangle and a trapezium instead of counting squares by eye.
How this paper was built
This is a TutorZone original drilling mock: the questions follow the Cambridge 9702 structure (Paper 3, 40 marks, 2 hours, practical skills) and the answers are our own, not Cambridge past papers or marking references.
Every numeric answer was recomputed programmatically (resistivity, percentage uncertainty, curve area).
Pacing
| Section | Marks | Suggested time | What to do first |
|---|---|---|---|
| Paper 3 (Advanced Practical Skills) | AS 23%／A Level 11.5% | about 60 min per question | measurement, uncertainty, graphs |
| Paper 2 (AS structured) | AS 46%／A Level 23% | about 15 min per question | formula, substitution, units |
| Paper 4 (A Level structured) | A Level 38.5% | about 11 min per question | A2 explanation and calculation |
Which skills carry the marks on Paper 3?
Four groups: instrument and precision (micrometer 0.01 mm, vernier 0.1 mm, range), recording and significant figures, uncertainty (percentage, powers, combining), and graphs (gradient with its unit, area under a curve, line of best fit). Method statements earn more than arithmetic.
Paper 3: practical-skills drilling (6 parts, 40 marks)
Time the full 2 hours: instrument and precision first, readings and uncertainty next.
Question 1 (4 marks)
Which instrument do you use for the diameter of a metal wire, what is its precision, and why take three readings at different positions?
Question 2 (8 marks)
For L = 0.200, 0.400, 0.600, 0.800 m the resistance is R = 0.87, 1.74, 2.60, 3.47 ohm. Plot R against L, find the gradient with its unit, and state what the gradient represents.
Question 3 (5 marks)
The three diameter readings are 0.38, 0.39 and 0.38 mm. Find the mean diameter, the cross-sectional area and the resistivity, to 2 significant figures.
Question 4 (3 marks)
Work out the percentage uncertainty in the diameter and in the gradient, and hence the uncertainty in the resistivity.
Question 5 (10 marks)
A rubber band is loaded: from x = 0 to 0.050 m the force rises linearly to 5.0 N, then flattens so that F = 6.5 N at x = 0.080 m. Find the work done (area under the curve).
Question 6 (10 marks)
Continuing from the previous question: how far below the linear-spring prediction is the force at x = 0.080 m? Identify one systematic error and suggest two changes that reduce the uncertainty.
How should Paper 3 be drilled?
Skill by skill, then whole papers: a first pass on instruments, readings and uncertainty, a second on graphs, gradients and areas, and only then a timed 2-hour paper. Mark against the point list each time, checking units and significant figures.
Paper 3 answers and mark points
Question 1
A micrometer screw gauge, precision 0.01 mm (2 marks); the wire is not perfectly uniform, so three positions averaged reduce the random error (2 marks).
Question 2
The four points lie close to a straight line; the gradient through the first and last points is (3.47 – 0.87) / (0.800 – 0.200) = 4.33 ohm per metre (6 marks); since R = rho L / A, the gradient is rho / A (2 marks).
Question 3
Mean diameter = 0.383 mm (1 mark); A = pi d^2 / 4 = 1.15 x 10^-7 m^2 (2 marks); rho = gradient x A = 4.33 x 1.15 x 10^-7 = 5.0 x 10^-7 ohm m (2 marks).
Question 4
Diameter: 0.01 / 0.383 x 100% = 2.6%, so the area carries 5.2%; the gradient about 1.8%; adding gives rho = 4.33 x 1.15 x 10^-7 +/- 7%, i.e. (5.0 +/- 0.4) x 10^-7 ohm m.
Question 5
First part (triangle): 0.5 x 5.0 x 0.050 = 0.125 J (3 marks); second part (trapezium): 0.5 x (5.0 + 6.5) x 0.030 = 0.173 J (5 marks); total about 0.30 J (2 marks).
Question 6
The linear model predicts F = 5.0 x (0.080 / 0.050) = 8.0 N against 6.5 N measured, i.e. 18.8% lower (3 marks); systematic error: an uncorrected zero reading / the zero of the rule (3 marks); changes: wait for the band to settle before each reading, measure the extension with vernier calipers or from a photograph, repeat three times and average (4 marks, 2 each for two changes).
How should the 2 hours be split?
About 60 minutes per question: five minutes reading and listing instruments with precision, forty minutes on readings, tables, graphs and calculation, and the last fifteen on uncertainty, error evaluation and improvements – the part most often left too thin.
Where these marks are usually lost
| Mistake | What it looks like | What it costs | Instead |
|---|---|---|---|
| Doubling forgotten | Same % for area | A goes as d squared | 2.6% -> 5.2% |
| Gradient without unit | Just 4.33 | R/L is ohm per metre | 4.33 ohm m^-1 |
| Counting squares by eye | A guessed number | Triangle plus trapezium | 0.125 + 0.173 J |
| No instrument precision | ‘Use a micrometer’ | State 0.01 mm | 0.01 mm |
How to use this paper
First drill: the full 2 hours on all six parts, no notes.
Mark it: check the instrument precision, the units and whether the area factor was applied to the uncertainty (2.6% to 5.2%).
Second drill: redo three to seven days later, aiming to finish inside 1 h 40.
How many years of Paper 3 past papers is enough?
The 2025-2027 syllabus states no significant changes affecting teaching and the five-paper structure is unchanged, so Paper 3 papers from 2022 onwards (about five series) can be drilled whole; older papers are better mined for a single skill, such as the gradient question, because instruments and contexts change.
FAQ
Is this a Cambridge past paper?
No. The questions and answers are TutorZone originals, not Cambridge past papers or marking references.
What does A-Level Physics 9702 Paper 3 test?
Advanced practical skills: instruments and precision, measurement and recording, uncertainty, gradients and areas, error evaluation; 40 marks in 2 hours, 23% of AS and 11.5% of the A Level.
Why is the diameter uncertainty doubled?
Because A = pi d^2 / 4 goes as the square of d, and a power multiplies the percentage uncertainty by that power.
Must the Paper 3 experiment be inside the syllabus content?
No. The syllabus says the context may be outside the syllabus content, so method beats memorised procedures.
Official references
| Resource | What to check |
|---|---|
| Cambridge A-Level Physics 9702 syllabus (2025-2027) | Confirm the Paper 3 marks, time and practical skills |
| https://www.tutorzone.com.hk/en-alevel-physics-9702-past-paper-drill-guide/ | A-Level Physics 9702 drilling guide (paper order and 12-week plan) |
| https://www.tutorzone.com.hk/en-alevel-physics-9702-paper-4-mock-2027/ | A-Level Physics Paper 4 drilling mock |
Related: practice area · A-Level Physics 9702 drilling guide · A-Level Physics Paper 4 drilling mock
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