October 2024 Edexcel Physics IAL Unit 3 (WPH13/01) Mark Scheme

byO/A Note -Monday, July 27, 2026

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Document Type: Pearson Edexcel International Advanced Subsidiary Level Physics Mark Scheme (Practical Skills in Physics I).
Paper Code: WPH13/01 (October 2024).
Total Questions: 4 comprehensive practical and experimental skill questions.

Uncertainty & Errors: Calculate percentage uncertainty for small measurements (0.39%) and account for zero errors to eliminate systematic error.
Density Determination: Determine density by measuring mass with a balance, calculating the volume of a sphere using:
$V = \frac{4}{3} π r^{3}$
Then calculate density using:
$ρ = \frac{m}{V}$
Terminal Velocity Procedure: Measure the time taken over a fixed distance between rubber bands, avoid parallax error, and verify that terminal velocity has been reached.
Conclusion: Calculate the lower limit or determine the percentage difference (11%) to assess whether the liquid is castor oil.

Circuit Design: Construct a circuit using:
- Power supply
- Ammeter connected in series
- Voltmeter connected in parallel across the sealed box
- Variable resistor
Component Protection: Use a fixed resistor to limit the maximum current and prevent short circuits when the diode is reverse-biased.
Resistor Selection: Calculate the required resistance (27 Ω) and power rating (0.85 W) before selecting the appropriate resistor (Resistor D).
Diode Behaviour: Use the negative potential difference readings to conclude that the components are connected in parallel.

Measurement Techniques: Reduce experimental error by:
- Using a set square.
- Clamping the metre rule vertically close to the beaker.
- Reading measurements perpendicular to the scale to avoid parallax error.
Data Evaluation: Identify errors including:
- Inconsistent decimal places.
- No repeat measurements.
- Too few data points.
- Anomalous values.
Mean & Uncertainty: Calculate:
- Mean value = 1.35
- Percentage uncertainty from half-range = 4%

Linear Equation Matching: Compare:
$K = (\frac{M_{B}}{M_{A}}) L + \frac{0.2 M_{R}}{M_{A}}$
with
$y = m x + c$
Hence derive:
$M_{R} = 5 \times y - intercept \times M_{A}$
Graph Plotting: Plot a graph with correctly labelled axes (K / m against L / m), use sensible scales, accurately plot all points, and draw a suitable line of best fit.
Calculations:
- Gradient = 0.237–0.249
- Mass of M_B = 97 g
- Mass of M_R = 124 g