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Revision guide · A-Level

A-Level Physics practical skills: Cambridge Papers 3 and 5 and the Edexcel IAL core practicals

'Required practicals' is AQA's term. The boards used most in the Gulf assess practical work differently. Cambridge 9702 has no list of set experiments: Paper 3 (Advanced Practical Skills, 2 hours, 40 marks) is a laboratory exam with two experiments that may be outside the syllabus content, and Paper 5 (Planning, Analysis and Evaluation, 1 hour 15 minutes, 30 marks) is a written paper on designing experiments and analysing data. Edexcel IAL names 16 core practicals and examines them in written papers, Units 3 (WPH13) and 6 (WPH16), and in theory papers. Either way, marks come from the same skills: tables, graphs, gradients, uncertainties and evaluation.

Facts checked:

At a glance

Cambridge 9702 Paper 3
Practical test, 2 h, 40 marks, two questions
Cambridge 9702 Paper 5
Written, 1 h 15 min, 30 marks, planning and analysis
Edexcel IAL
16 core practicals; WPH13 and WPH16 written practical papers
Key skill
Uncertainties and straight-line graphs

The Edexcel IAL Physics core practicals

UnitCore practicals
Unit 1 Mechanics and MaterialsCP1 acceleration of a freely-falling object; CP2 viscosity by a falling-ball method; CP3 Young modulus of a material
Unit 2 Waves and ElectricityCP4 speed of sound with a 2-beam oscilloscope; CP5 frequency of a vibrating string (length, tension, mass per unit length); CP6 wavelength of light with a diffraction grating; CP7 electrical resistivity; CP8 e.m.f. and internal resistance of a cell
Unit 4 Further Mechanics, Fields and ParticlesCP9 force and change of momentum; CP10 collisions between small spheres analysed with ICT; CP11 capacitor charging and discharging with an oscilloscope or data logger
Unit 5 Thermodynamics, Radiation, Oscillations and CosmologyCP12 calibrating a thermistor in a potential divider as a thermostat; CP13 specific latent heat; CP14 pressure and volume of a gas at fixed temperature; CP15 absorption of gamma radiation by lead; CP16 unknown mass from resonant frequencies of oscillation

Cambridge 9702 does not list set practicals. Paper 3 has two questions of 1 hour and 20 marks each, set in different areas of physics, and Paper 5 has two questions of 15 marks each.

The key ideas

Absolute uncertainty is the range a reading could lie within, such as ±0.01 mm on a micrometer. Percentage uncertainty is absolute uncertainty divided by the value, times 100. When quantities are multiplied or divided, add percentage uncertainties; when a quantity is raised to a power, multiply its percentage uncertainty by the power. When quantities are added or subtracted, add absolute uncertainties.

Most practical analysis turns a relationship into a straight line, y = mx + c. For a pendulum, T = 2π sqrt(l/g), so plotting T^2 against l gives a straight line through the origin with gradient 4π^2/g. For resistance of a wire, R = ρL/A, so R against L has gradient ρ/A. Choose the axes so the unknown comes from the gradient or intercept.

Good tables have a column heading with quantity and unit (such as T / s), consistent decimal places matching the instrument's precision, and repeat readings where appropriate. Good graphs use more than half the grid, have clearly plotted points, and a line of best fit; the gradient triangle should be large.

Worked example 1: combining uncertainties for resistivity

  1. R = 12.0 ± 0.2 Ω, L = 1.50 ± 0.01 m, d = 0.40 ± 0.01 mm.
  2. Percentage uncertainties: R, 0.2 ÷ 12.0 = 1.7%; L, 0.01 ÷ 1.50 = 0.7%; d, 0.01 ÷ 0.40 = 2.5%.
  3. Area depends on d^2, so its percentage uncertainty is 2 × 2.5 = 5.0%.
  4. ρ = RA/L, so add: 1.7 + 5.0 + 0.7 = 7.4%.
  5. With ρ = 1.01 × 10^-6 Ω m, the absolute uncertainty is about 0.07 × 10^-6, so ρ = (1.01 ± 0.07) × 10^-6 Ω m. The diameter dominates, so measuring it more precisely matters most.

Worked example 2: finding g from a pendulum graph

  1. A graph of T^2 (s^2) against l (m) is a straight line through the origin with gradient 4.02 s^2 m^-1.
  2. From T^2 = (4π^2/g) l, the gradient = 4π^2/g.
  3. g = 4π^2 ÷ 4.02 = 9.82 m s^-2.
  4. If the line did not pass through the origin, that would suggest a systematic error, such as measuring l to the top of the bob instead of its centre.

Common mistakes that cost marks

  • Table headings without units, or units written in each cell instead of the heading.
  • Inconsistent decimal places in a column of raw readings.
  • Small graph scales, awkward scales such as 3 units per square, or plotting points as large dots.
  • Using data points rather than points on the best-fit line for the gradient triangle.
  • Vague improvements such as 'be more careful' or 'use better equipment'. Name the specific change and why it helps.
  • Confusing random errors (scatter, reduced by repeats) with systematic errors (offset, not reduced by repeats).

Exam technique and how a tutor helps

For Cambridge Paper 3, practise working to time: about an hour for each experiment, with readings recorded straight into a table. For Paper 5, learn the structure of a plan: identify the independent and dependent variables, the control variables, the method of measuring each, the analysis (which graph and how the constant comes from it) and safety. For Edexcel WPH13 and WPH16, know each core practical well enough to describe the method, sources of uncertainty and improvements, because questions are set on them in writing.

Online lessons cannot replace a school laboratory, and students should do the experiments at school. What a tutor can do one to one is the analysis: working through real data sets, uncertainty calculations, graph drawing and planning questions from past papers, with the tutor checking every table heading, scale and gradient on the shared whiteboard.

Self-check: can you do these?

  • A length is 25.0 ± 0.1 cm. What is its percentage uncertainty? (Answer: 0.4%)
  • A radius has 2% uncertainty. What is the percentage uncertainty in the volume of a sphere? (Answer: 6%)
  • What graph gives a straight line for V = IR with R constant? (Answer: V against I, gradient R)
  • Name one Edexcel IAL core practical from Unit 2. (Answer: for example, CP7 resistivity)
  • Which Cambridge 9702 paper tests planning an experiment? (Answer: Paper 5)

Common questions

Does Cambridge A-Level Physics have required practicals?

No. The 9702 syllabus does not list set experiments. Practical skills are assessed in Paper 3, a 2-hour practical test with two experiments that may be outside the syllabus content, and Paper 5, a written paper on planning, analysis and evaluation.

How are Edexcel IAL core practicals assessed?

In written papers. Units 3 (WPH13) and 6 (WPH16) are written practical skills papers, and the 16 core practicals can also appear in the theory units. There is no separate laboratory exam.

What is AQA's practical endorsement?

AQA A-level Physics uses 'required practicals' and a separately reported practical endorsement. Schools in the Gulf more often use Cambridge or Edexcel IAL, so check which board your child is entered for.

Can practical skills be practised online?

The experiments themselves need a school lab, but the analysis, uncertainties, graphs and planning that earn most of the marks can be practised one to one with real data from past papers.

How much do LiveTutor A-Level Physics lessons cost?

Every lesson is one to one, online and 60 minutes, at one flat rate of $15 a lesson for every subject and level. Families choose a weekly plan of 1 to 5 lessons billed monthly, and the first lesson is a free trial.

Sources

Dates and figures on this page come from these official and published sources. Always confirm deadlines on the official page before acting on them.

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