Required practicals and the practical endorsement

6 min readA-Level Physics

Practical work is examined twice. In England your teacher assesses the practical endorsement (CPAC), and separately at least 15% of written-paper marks test practical knowledge: on AQA, the 45-mark Paper 3 Section A plus questions in Papers 1 and 2. Examiners assume you did every practical. They ask for the method, the graph, what the gradient means, the dominant uncertainty and a specific improvement. Here are all five for each AQA required practical, with other boards’ equivalents.

The twelve AQA required practicals

Edexcel core practical numbers are shown where the experiment is the same. OCR covers the same experiments in its Practical Activity Groups (PAGs).

RP	Experiment and key method	Plot → result	Dominant uncertainty → improvement	Edexcel
1	Stationary waves on a string: vibration generator and pulley with hanging masses; adjust $f$ until the first harmonic forms; vary $l$ , then $T$ , then $\mu$	$f$ against $1/l$ ; gradient $= \frac{1}{2}\sqrt{T/\mu}$	Judging exactly when resonance occurs → approach it from above and below and average; use a stroboscope to locate nodes	CP7
2	Young’s slits and grating: laser, slits, screen 1–2 m away; measure across many fringes; grating angles from positions of the maxima	$w$ against $D$ ; $\lambda = s \times$ gradient. Grating: $d\sin\theta = n\lambda$
3	$g$ by free fall: electromagnet and trapdoor, or light gates; vary height $h$	$h$ against $t^2$ ; $g = 2 \times$ gradient
4	Young modulus: long thin wire (about 2 m) with a marker against a fixed scale or reference wire; micrometer for diameter	$F$ against $\Delta L$ (linear region); $E = \text{gradient} \times L/A$	Extension is only a few mm → use a longer wire and a vernier scale; diameter is squared → measure it at several points and orientations	CP5
5	Resistivity: micrometer; crocodile clip moved along the wire; ammeter and voltmeter	$R$ against $L$ ; $\rho = \text{gradient} \times A$	Diameter (squared) → repeat readings; heating raises $R$ → small current, switch off between readings. The gradient removes contact resistance
6	EMF and internal resistance: cell, variable resistor, protective resistor; record $V$ and $I$	$V$ against $I$ ; intercept $= \varepsilon$ , gradient
7	SHM: mass on a spring (vary $m$ ) and simple pendulum (vary $l$ )	$T^2$ against $m$ gives $k = 4\pi^2/\text{gradient}$ ; against gives
8	Boyle’s and Charles’s laws: Boyle: compress trapped air slowly at constant $T$ . Charles: air column in a capillary tube in a stirred water bath	Boyle: $p$ against $1/V$ is a straight line through the origin. Charles: $V$ against $\theta$ extrapolates to about
9	Capacitor charge and discharge: data logger, or a stopwatch with a large time constant	$\ln V$ against $t$ ; gradient $= -1/RC$	Reading a changing meter → use a data logger or make $RC$ at least 30 s; start timing exactly as the switch moves	CP11
10	Force on a wire: magnets on a top-pan balance, wire clamped rigidly through the field; balance change $\times g$ gives $F$	$F$ against $I$ ; $B = \text{gradient}/L$
11	Search coil: coil at angle $\theta$ in an alternating field, output on an oscilloscope	peak emf against $\cos\theta$ : straight line through the origin	Reading the peak on the trace → increase the Y-gain so the trace fills the screen and read peak-to-peak; align the protractor carefully	–
12	Inverse-square law for γ: GM tube and counter; measure the background count first	$(C - C_0)^{-1/2}$ against $d$ : straight line, with -intercept (the source’s hidden offset)

Other boards’ practicals

Edexcel 9PH0 (16 core practicals) adds viscosity by falling ball (CP4), the speed of sound with a two-beam oscilloscope (CP6), momentum with light gates (CP9), collisions by video analysis (CP10), thermistor calibration (CP12), specific latent heat (CP13) and γ absorption by lead (CP15: $\ln C$ against thickness).
OCR A and OCR B use 12 PAGs: PAG1–9 are structured practicals, PAG10–11 open investigations and PAG12 research skills. OCR B also has a 60-mark practical paper.
Eduqas specified practicals are examined in the written components.
Edexcel IAL tests practical skills in written Units 3 and 6 (50 marks each): planning, data handling, uncertainties and evaluation.

The practical endorsement (CPAC)

In England (AQA, Edexcel, OCR A/B, Eduqas) your teacher judges you against five Common Practical Assessment Criteria over at least 12 practicals:

Following written procedures correctly.
Applying investigative approaches when using instruments and equipment.
Using equipment and materials safely.
Making and recording observations accurately.
Researching, referencing and reporting.

It is reported as Pass or Not Classified, separately from your grade, but science and engineering courses often require a Pass. Keep your lab book complete: dated entries, raw data tables with units, and a reference for any data you did not measure.

Practical exams

Cambridge 9702 Paper 3: two timed experiments of about an hour each, 20 marks each, carried out in a real laboratory. Paper 5 is a written planning and analysis paper. See the Cambridge 9702 guide for the table, graph and evaluation marking.
WJEC Unit 5 (10%): an experimental task in the laboratory plus a written practical analysis task.
CCEA AS 3 and A2 3: Booklet A is timetabled practical tasks (about 1 hour) and Booklet B is data analysis (about 1 hour).

All of them reward the same habits: raw readings to the instrument’s resolution, headings as quantity / unit, at least six values over a wide range, and a large graph with a gradient triangle covering more than half the line.

How practical questions are marked

Improvements must be specific and justified. “Use more accurate equipment” scores nothing. “Use a vernier scale (resolution 0.1 mm) to reduce the percentage uncertainty in the extension” scores.
Safety must match the hazard. Laser: do not look along the beam and keep it below eye level. Loaded wire: goggles, plus a sand tray under the masses. Radioactive source: tongs, and return it to its lead box straight after use.
Method descriptions (often 6 marks): apparatus, independent variable, dependent variable, controls, range and repeats, graph, result from gradient or intercept.
Unfamiliar contexts hide a required practical. “A data logger records the pd across a capacitor” is RP9. Name the parent practical first.

Revising the practicals

Make one card per practical from memory: a labelled diagram, the variables, the graph and its gradient, the main uncertainty with its improvement, and one hazard with its control. Review the cards with spaced retrieval, then answer Courselo’s practical-skills bank questions under timed conditions.

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Required practicals and the practical endorsement

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Required practicals and the practical endorsement

6 min readA-Level Physics

The twelve AQA required practicals

Edexcel core practical numbers are shown where the experiment is the same. OCR covers the same experiments in its Practical Activity Groups (PAGs).

RP	Experiment and key method	Plot → result	Dominant uncertainty → improvement	Edexcel
1	Stationary waves on a string: vibration generator and pulley with hanging masses; adjust $f$ until the first harmonic forms; vary $l$ , then $T$ , then $\mu$	$f$ against $1/l$ ; gradient $= \frac{1}{2}\sqrt{T/\mu}$	Judging exactly when resonance occurs → approach it from above and below and average; use a stroboscope to locate nodes	CP7
2	Young’s slits and grating: laser, slits, screen 1–2 m away; measure across many fringes; grating angles from positions of the maxima	$w$ against $D$ ; $\lambda = s \times$ gradient. Grating: $d\sin\theta = n\lambda$
3	$g$ by free fall: electromagnet and trapdoor, or light gates; vary height $h$	$h$ against $t^2$ ; $g = 2 \times$ gradient
4	Young modulus: long thin wire (about 2 m) with a marker against a fixed scale or reference wire; micrometer for diameter	$F$ against $\Delta L$ (linear region); $E = \text{gradient} \times L/A$	Extension is only a few mm → use a longer wire and a vernier scale; diameter is squared → measure it at several points and orientations	CP5
5	Resistivity: micrometer; crocodile clip moved along the wire; ammeter and voltmeter	$R$ against $L$ ; $\rho = \text{gradient} \times A$	Diameter (squared) → repeat readings; heating raises $R$ → small current, switch off between readings. The gradient removes contact resistance
6	EMF and internal resistance: cell, variable resistor, protective resistor; record $V$ and $I$	$V$ against $I$ ; intercept $= \varepsilon$ , gradient
7	SHM: mass on a spring (vary $m$ ) and simple pendulum (vary $l$ )	$T^2$ against $m$ gives $k = 4\pi^2/\text{gradient}$ ; against gives
8	Boyle’s and Charles’s laws: Boyle: compress trapped air slowly at constant $T$ . Charles: air column in a capillary tube in a stirred water bath	Boyle: $p$ against $1/V$ is a straight line through the origin. Charles: $V$ against $\theta$ extrapolates to about
9	Capacitor charge and discharge: data logger, or a stopwatch with a large time constant	$\ln V$ against $t$ ; gradient $= -1/RC$	Reading a changing meter → use a data logger or make $RC$ at least 30 s; start timing exactly as the switch moves	CP11
10	Force on a wire: magnets on a top-pan balance, wire clamped rigidly through the field; balance change $\times g$ gives $F$	$F$ against $I$ ; $B = \text{gradient}/L$
11	Search coil: coil at angle $\theta$ in an alternating field, output on an oscilloscope	peak emf against $\cos\theta$ : straight line through the origin	Reading the peak on the trace → increase the Y-gain so the trace fills the screen and read peak-to-peak; align the protractor carefully	–
12	Inverse-square law for γ: GM tube and counter; measure the background count first	$(C - C_0)^{-1/2}$ against $d$ : straight line, with -intercept (the source’s hidden offset)

Other boards’ practicals

Edexcel 9PH0 (16 core practicals) adds viscosity by falling ball (CP4), the speed of sound with a two-beam oscilloscope (CP6), momentum with light gates (CP9), collisions by video analysis (CP10), thermistor calibration (CP12), specific latent heat (CP13) and γ absorption by lead (CP15: $\ln C$ against thickness).
OCR A and OCR B use 12 PAGs: PAG1–9 are structured practicals, PAG10–11 open investigations and PAG12 research skills. OCR B also has a 60-mark practical paper.
Eduqas specified practicals are examined in the written components.
Edexcel IAL tests practical skills in written Units 3 and 6 (50 marks each): planning, data handling, uncertainties and evaluation.

The practical endorsement (CPAC)

In England (AQA, Edexcel, OCR A/B, Eduqas) your teacher judges you against five Common Practical Assessment Criteria over at least 12 practicals:

Following written procedures correctly.
Applying investigative approaches when using instruments and equipment.
Using equipment and materials safely.
Making and recording observations accurately.
Researching, referencing and reporting.

Practical exams

Cambridge 9702 Paper 3: two timed experiments of about an hour each, 20 marks each, carried out in a real laboratory. Paper 5 is a written planning and analysis paper. See the Cambridge 9702 guide for the table, graph and evaluation marking.
WJEC Unit 5 (10%): an experimental task in the laboratory plus a written practical analysis task.
CCEA AS 3 and A2 3: Booklet A is timetabled practical tasks (about 1 hour) and Booklet B is data analysis (about 1 hour).

How practical questions are marked

Improvements must be specific and justified. “Use more accurate equipment” scores nothing. “Use a vernier scale (resolution 0.1 mm) to reduce the percentage uncertainty in the extension” scores.
Safety must match the hazard. Laser: do not look along the beam and keep it below eye level. Loaded wire: goggles, plus a sand tray under the masses. Radioactive source: tongs, and return it to its lead box straight after use.
Method descriptions (often 6 marks): apparatus, independent variable, dependent variable, controls, range and repeats, graph, result from gradient or intercept.
Unfamiliar contexts hide a required practical. “A data logger records the pd across a capacitor” is RP9. Name the parent practical first.

Revising the practicals

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