CIE A Level Physics
CIE A Level Physics Measurement Techniques Exam Questions
Free CIE A Level Physics exam questions for Measurement Techniques, with a mark scheme for every pack. Covers measuring instruments, errors and uncertainties, accuracy and precision, combining uncertainties and analysing experimental data.
Measurement Techniques exam questions
1 question pack of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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About CIE A Level Physics Measurement Techniques
Measurement techniques underpin the whole Cambridge International AS & A Level Physics (9702) course. You need to read instruments correctly, estimate and combine uncertainties, and judge whether data are accurate and precise. These skills are tested directly in Paper 3 (Advanced Practical Skills) and Paper 5 (Planning, Analysis and Evaluation), and they also appear in written papers whenever a calculation asks for an uncertainty. Examiners look for correct significant figures, sensible repeat readings, clear tables with units, and uncertainties that are combined using the right rule for addition, multiplication or powers.
What you need to know
- Instruments and resolution Know how to use metre rules, vernier calipers, micrometer screw gauges, stopwatches, ammeters, voltmeters and an oscilloscope. Record readings to the resolution of the instrument and check for zero error before measuring.
- Random and systematic errors Random errors scatter readings either side of the true value and are reduced by repeating and averaging. Systematic errors shift every reading by the same amount (for example a zero error) and are not reduced by repeating.
- Accuracy and precision Accuracy is how close a result is to the true value. Precision is how close repeated readings are to each other, shown by a small spread.
- Combining uncertainties When adding or subtracting quantities, add absolute uncertainties. When multiplying or dividing, add percentage (fractional) uncertainties. For a power, multiply the percentage uncertainty by the power.
- Oscilloscope readings Read time from the time-base setting (time per division) and voltage from the y-gain (volts per division). Period = number of divisions for one cycle × time-base; frequency = 1/period.
- Graphs and gradients Plot data on a large scale, draw a best-fit line and a worst acceptable line, and use the difference in gradients to estimate the uncertainty in the gradient.
Common mistakes in Measurement Techniques
- Adding absolute uncertainties when multiplying quantities. Use percentage uncertainties for products and quotients.
- Saying repeating readings removes systematic error. Repeats only reduce the effect of random error; systematic error needs recalibration or correction.
- Quoting a final answer to far more significant figures than the data support. Match the number of significant figures to the least precise measurement.
- Forgetting to double the percentage uncertainty of a diameter when calculating cross-sectional area. Area depends on d squared, so its percentage uncertainty is twice that of d.
- Confusing precision with accuracy. A set of readings can be very close together and still all be wrong because of a systematic error.
Try three Measurement Techniques exam-style questions
1. The diameter of a wire is measured as 0.52 ± 0.01 mm. Calculate the percentage uncertainty in the cross-sectional area of the wire. (2 marks)
Show the mark scheme answer
Percentage uncertainty in d = (0.01/0.52) × 100 = 1.9%; area depends on d^2 so percentage uncertainty = 2 × 1.9 = 3.8% (accept 4%).
2. Explain the difference between a random error and a systematic error, and state how each can be reduced. (4 marks)
Show the mark scheme answer
Random error causes readings to scatter unpredictably about the true value; reduced by taking repeat readings and averaging; systematic error causes all readings to differ from the true value by the same amount or proportion; reduced by checking for zero error or recalibrating the instrument.
3. A micrometer has a zero error of +0.02 mm. It gives a reading of 3.46 mm for the thickness of a sheet. State the corrected thickness. (1 mark)
Show the mark scheme answer
Corrected thickness = 3.46 - 0.02 = 3.44 mm.
Measurement Techniques FAQs
What does Cambridge AS & A Level Physics measurement techniques cover?
It covers using measuring instruments, identifying random and systematic errors, distinguishing accuracy from precision, and estimating and combining uncertainties in measured and calculated quantities.
Which papers test measurement techniques?
The skills are central to Paper 3 (Advanced Practical Skills) and Paper 5 (Planning, Analysis and Evaluation), and uncertainty calculations can also appear in the written theory papers.
What rules do I need for combining uncertainties?
Add absolute uncertainties for sums and differences, add percentage uncertainties for products and quotients, and multiply the percentage uncertainty by n for a quantity raised to the power n.
