Practical questions
You will complete 21 required practical activities if you are studying GCSE Combined Science: Trilogy. You could be asked questions about the apparatus, methods, safety precautions, results, analysis and evaluation of these experiments.
There will be a number of different types of practical based questions. Some will be on the set required practicals, some will cover the working scientifically terms and some will be on other science practicals which you might have done in class. Use all the information given in the question particularly any diagrams to help you understand what the question is about.
This page contains AQA material which is reproduced by permission of AQA.
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Dr Alex Lathbridge answers questions about practicals.
Sample question 1 - Foundation/Higher
Question
Describe how a Leslie cube and other equipment could be used to compare how the type of surface affects the amount of infrared radiation emitted.
Suggest any safety precautions
Your answer should include any steps necessary to reduce inaccuracies in the data. [6 marks]
- fill a Leslie cube with water from a freshly boiled kettle
- use an infrared detector (eg thermopile) to detect the radiation coming off of each surface
- tabulate the results of surface type and reading from infrared emitter
Safety:
- boiling water - pour carefully at armâs length from the kettle
- support the Leslie cube on a heat resistant mat
- do not touch the hot cube
Reduce inaccuracies:
- allow a minute for the surfaces of the Leslie cube to warm up before beginning to take measurements
- ensure the infrared detector is the same distance from each surface
- repeat readings in case surfaces have cooled significantly between measurements
[1] for any bullet point up to a maximum of six.
Sample question 2 - Foundation/Higher
Question
An investigation is made into how the mass used to keep a wire under tension affects the wavelength of waves on the wire when oscillated by a vibration generator.
A wooden bridge supporting the wire is moved until two loops (equivalent to one wavelength) is seen after adjusting the masses used.
The experiment is done again to obtain a repeat set of readings.
The diagram illustrates this arrangement:
The frequency of the vibration generator and power supply is 50 Hz.
The table shows the data collected:
| Mass (g) | One Wavelength (cm) - First attempt | One Wavelength (cm) - Repeated attempt |
| 100 | 40.1 | 39.9 |
| 200 | 28.0 | 28.3 |
| 300 | 23.1 | 28.6 |
| 400 | 19.9 | 20.1 |
| Mass (g) | 100 |
|---|---|
| One Wavelength (cm) - First attempt | 40.1 |
| One Wavelength (cm) - Repeated attempt | 39.9 |
| Mass (g) | 200 |
|---|---|
| One Wavelength (cm) - First attempt | 28.0 |
| One Wavelength (cm) - Repeated attempt | 28.3 |
| Mass (g) | 300 |
|---|---|
| One Wavelength (cm) - First attempt | 23.1 |
| One Wavelength (cm) - Repeated attempt | 28.6 |
| Mass (g) | 400 |
|---|---|
| One Wavelength (cm) - First attempt | 19.9 |
| One Wavelength (cm) - Repeated attempt | 20.1 |
State with a reason which reading appears to be in error and what should be done to find the speed of waves in the string in each case? [4 marks]
The reading mass = 300 g, wavelength = 28.6 cm is likely to be in error [1] because it does not follow the pattern of the other readings which show a clear decrease in wavelength as more mass is added [1].
To find the speed of the waves in each case:
- find the average wavelengths for each mass [1]
- use v = fλ to find the wave speed (frequency is already given as 50 Hz) [1]
A working solution would either make the image larger or allow the student to see the smaller image more clearly.