Lesson 9 of 9
Insulation
Goal: Explain how insulators reduce energy transfer.
A thermal insulator slows down the transfer of energy from a hot place to a cold place.
- Trapped air is a very good insulator. Air is a poor conductor. Trapped in small pockets it cannot flow, so it cannot carry energy away by convection either. Wool, feathers, foam and bubble wrap all trap air.
- Shiny surfaces reflect radiation. Foil behind a radiator sends energy back into the room.
- A coat is not a source of energy. It keeps you warm by slowing the transfer of energy from your body to the cold air.
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Key words in this lesson
Convection A heated liquid or gas rises and carries energy with it
Radiation Energy transferred by waves, even across empty space
Thermal insulator A material that lets energy through only slowly