Many thermal insulators, such as loft insulation, contain pockets of trapped air. Why does trapping air make a material a more effective thermal insulator?
trapped air is at a higher temperature, so less energy is transferred through it
trapped air is denser than the material, so energy is transferred through it slowly
trapped air can be squashed, so it stores the energy that passes through the material
trapped air has a low thermal conductivity, so conduction through the material is slow
40 exam-style questions on AQA GCSE Physics 1.2 Conservation and dissipation of energy, covering 1.2.1 Energy transfers in a system and 1.2.2 Efficiency. Each one has a worked solution and a mark scheme showing where the marks go.