Instrument choice sets the measurement limits
Resolution, range and zero offset affect what can be inferred from a reading. Choosing a suitable instrument is part of deciding the uncertainty, not a separate administrative step.
Follow the reasoning
- Choose a range appropriate to the expected value.
- Check calibration or zero offset where possible.
- Record a justified uncertainty alongside the reading.
Try it in a past paper 5
Open the question, then use its mark scheme to check your work.
Question 22
Evaluate a refractive-index identification and describe an accurate critical-angle measurement.
Question 2
Use repeated diameter readings, density and upthrust to analyse a floating cylinder.
Question 3
Measure a falling ball’s height and time, then determine g and its uncertainty from a graph.
Question 21(b)–(c)
Determine Young modulus and evaluate measurement uncertainty.
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Question 7
Analyse a resonance-tube graph to determine sound speed and its uncertainty.
A curated collection checked against the question papers and mark schemes; not a complete past-paper catalogue. Links open official OCR PDFs in a new tab.
Put the ideas to work
More practice is on its way
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Specification outcomes (5)
- 1.1.2(a) How to use a wide range of practical apparatus and techniques correctly.
- 1.1.2(b) Appropriate units for measurements.
- 2.2.1(a) Understand systematic errors (including zero errors) and random errors in measurements.
- 2.2.1(b) Understand precision and accuracy in the context of measurement.
- 2.2.1(c) Calculate absolute and percentage uncertainties when data are combined by addition, subtraction, multiplication, division or raising to powers.