Thermal Insulation (Edexcel GCSE Physics: Combined Science)

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Thermal Insulation

  • Thermal energy transfers from hotter areas to cooler areas by the processes of:
    • Conduction
    • Convection
    • Radiation

Heat loss, downloadable IGCSE & GCSE Physics revision notes

Conduction, convection and radiation demonstrated in a mug of hot tea

  • Objects will always lose heat until they are in thermal equilibrium with their surroundings
  • Thermal equilibrium is reached when objects have cooled to room temperature
  • Insulation can be used to reduce the rate at which heat transfers

Reducing Conduction

  • Insulators are materials that are poor conductors of heat
  • Fabrics, such as wool and cotton, are good insulators

Conductors and insulators, downloadable IGCSE & GCSE Physics revision notes

Different materials have different properties of conductivity

  • These materials are usually low density and often contain pockets of trapped air
    • This makes them very effective because air is a poor conductor

  • Surrounding a warm object with a material that contains trapped air will reduce the rate at which it loses heat
  • Likewise, surrounding a cold object with such a material will reduce the amount of heat reaching the object

Reducing Convection

  • Insulating materials that contain trapped air are also effective at reducing convection
  • Trapped air is unable to move around, forming convection currents
  • By placing a lid on a hot drink, or saucepan, convection can be further reduced

Reducing Radiation

  • Infrared radiation is emitted from all hot materials
    • It is a wave of electromagnetic radiation

  • Shiny materials are poor emitters of radiation
  • By covering the material with a shiny (non-metal) coating the rate of heat loss can be further reduced

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Ashika

Author: Ashika

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Ashika graduated with a first-class Physics degree from Manchester University and, having worked as a software engineer, focused on Physics education, creating engaging content to help students across all levels. Now an experienced GCSE and A Level Physics and Maths tutor, Ashika helps to grow and improve our Physics resources.