AQA GCSE Physics Physics Paper 2 (Higher), November 2021: Question 6
9 marks · Standard Demand difficulty · Short Answer
Calculate the mean frequency of water waves from ripple tank measurements, state the advantage of repeating measurements, and explain how to determine wave speed without measuring wavelength.
Practise this questionQuestion
Question text
06 A teacher demonstrated some features of waves using a ripple tank.
Figure 10 shows the ripple tank.
Figure 10
06.1 The teacher measured the time taken for 10 wave fronts to pass the mark.
The teacher repeated this measurement three times and calculated the mean.
What is the advantage of repeating measurements and calculating a mean?
[1 mark]
06.2 The teacher’s measurements for the time taken for 10 wave fronts to pass the
mark were:
8.4 s 7.8 s 8.1 s
Calculate the mean frequency of the wave.
Give your answer to 2 significant figures.
[5 marks]
Mean frequency (2 significant figures) = Hz
06.3 In a different investigation, the teacher wanted to determine the speed of water waves
in the ripple tank.
The teacher did not measure the wavelength of the wave.
Explain how the teacher could determine the speed of the wave.
[3 marks]
Mark scheme
Show the mark scheme
Question 6
AO /
Question Answers Extra information Mark
Spec. Ref.
06.1 to reduce the effect of random allow gives a more accurate 1 AO1
errors mean 4.6.1.2
ignore reference to anomalous
results
ignore measurements are more
accurate
06.2 (8.4+7.8+8.1) = 8.1 (s) 1 AO2
3 4.6.1.2
8.1 = 0.81 (s) 1
frequency = 1 . allow a correct substitution of an 1
0.81 incorrectly calculated value for
time
frequency = 1.2345… this mark may be awarded if the 1
time is incorrectly calculated
frequency = 1.2 (Hz) allow a calculated value 1
correctly rounded to 2 sig figs
06.3 measure the distance travelled allow measure the length of the 1 AO1
by a wave using a metre rule (ripple) tank using a metre rule 4.6.1.2
measure the time taken (for the 1
wave to travel the measured
distance) with a timer /
stopwatch
divide the distance by the time dependant on scoring the first 1
two mark points
Total 9
How to answer it
Waves Practical: Ripple Tanks
What this question tests
This question assesses your understanding of required practical techniques using a ripple tank, including how to collect reliable data, calculate wave frequency and period, and determine wave speed using distance and time measurements without wavelength.
Advantage of Repeating Measurements
✅ Correct Answer
To reduce the effect of random errors.
💡 Key Knowledge
- Repeating measurements allows you to calculate a mean, which makes your final value more reliable.
- Random errors are unpredictable variations in measurements caused by human error (like reaction time with a stopwatch).
❌ Common Errors
Do not write "to make the results more accurate" or "to find anomalous results" on their own — examiners strictly penalise these imprecise phrases for this specific mark point.
Calculating Mean Frequency
✅ Correct Answer
1.2 Hz
📐 Step-by-Step Calculation
- Find the mean time for 10 waves:
(8.4 + 7.8 + 8.1) / 3 = 8.1 s - Find the time for 1 wave (period, T):
8.1 / 10 = 0.81 s - Calculate frequency (f = 1 / T):
1 / 0.81 = 1.2345... Hz - Round to 2 significant figures:
1.2 Hz
🧠 Exam Technique & Traps
- Significant Figures: The question explicitly asks for 2 s.f. Forgetting to round loses the final mark.
- Equation Recall: Remember that frequency and period are linked by the formula f = 1 / T .
Determining Wave Speed Without Wavelength
✅ Correct Answers (3 Marks)
- Measure the distance travelled by a wave using a metre rule (or length of ripple tank).
- Measure the time taken to travel that distance using a stopwatch / timer.
- Divide the distance by the time ( speed = distance / time ).
🧠 Exam Technique
The third mark (dividing distance by time) is dependent on scoring the first two marks. You must clearly state what equipment is used to measure distance (metre rule) and time (stopwatch).
Topics
Physics · Required Practicals · Required Practicals · P6: Waves
Question and mark scheme from the AQA GCSE Physics examination, Physics Paper 2 (Higher), November 2021. QuestionVault is an independent revision resource; questions remain the copyright of the awarding body.