Thermal Insulation
Build confidence in Thermal Insulation for GCSE Physics with this free worksheet and full mark scheme — Foundation and Higher exam-style questions with worked answers for AQA, Edexcel and OCR. A separate (triple) physics topic: investigate how the thickness and type of insulating material affect the rate at which water cools.
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These worksheets and mark schemes are original, written for Virtus Academy and checked against the current AQA, Edexcel and OCR specifications. Every worksheet comes with a full mark scheme.
Topic overview
This required practical investigates the effectiveness of different materials as thermal insulators. This is a Triple-only topic.
A beaker of hot water is used as a model of a building. The beaker is wrapped in the insulating material being tested, and the temperature of the water is recorded at regular intervals as it cools. A better insulator produces a smaller temperature drop over the same period.
Control variables are essential: the starting temperature of the water, the volume of water, the thickness of the insulating material, and the time interval must all be kept the same. Only the material should change, or the comparison is not valid.
Revision notes
The method
Pour a measured volume of hot water into a beaker and record its starting temperature.
Wrap the beaker in the insulating material being tested. Record the temperature at regular intervals as it cools, then repeat with different materials and compare the temperature drops.
Control variables
The starting temperature and volume of the water must be the same each time.
The thickness of each insulating material must be the same, and the temperature must be measured at the same time intervals. Only the material being tested should change.
Interpreting results
A smaller temperature drop over the same time means a better insulator.
Also investigate the effect of thickness by using different numbers of layers of the same material. More layers reduce the rate of energy transfer further.
Key points
- A beaker of hot water models a building.
- The beaker is wrapped in the material being tested.
- Temperature is recorded at regular intervals.
- A smaller temperature drop means a better insulator.
- Keep the starting temperature and volume constant.
- Keep the thickness of each material the same.
Worked examples
Example 1
State three variables that must be controlled in this investigation. [3 marks]
Model answer
The starting temperature of the water (1 mark). The volume of water used (1 mark). The thickness of the insulating material (1 mark).
Example 2
Explain how you would know which material is the best insulator. [2 marks]
Model answer
Compare the temperature drop over the same period of time for each material (1 mark). The material giving the smallest temperature drop is the best insulator, because it transfers energy most slowly (1 mark).
Example 3
Explain why a lid is placed on the beaker. [2 marks]
Model answer
A lid reduces energy transfer from the surface of the water by evaporation and convection (1 mark), so the comparison tests the insulating material rather than losses from the open top (1 mark).
Common mistakes
Not controlling the thickness of the material.
Different thicknesses would make the comparison unfair.
Using different starting temperatures.
The temperature drop could not then be compared fairly.
Saying the best insulator cools fastest.
The best insulator gives the SMALLEST temperature drop.
Forgetting the lid.
Energy escaping from the open surface would mask the effect of the material.
Exam tips
- Name at least three control variables.
- Compare temperature drops over the same time period.
- Explain the lid in terms of surface energy loss.
- Remember this is a Triple-only required practical.
Key terms
- Insulator
- A material that transfers energy slowly.
- Control variable
- A variable kept constant for a fair test.
- Temperature drop
- The fall in temperature over a set period.
- Thermal conductivity
- How readily a material transfers energy by heating.
Related topics
Written and reviewed against the current AQA, Edexcel and OCR specifications. Spotted an error? Let us know.