Heat transfer

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Heat Transfer

Thermal radiation

Thermal radiation is energy transfer by electromagnetic waves.

All objects emit thermal radiation.

The hotter an object is, the more thermal radiation it emits.

The electromagnetic spectrum is the range of wavelengths or frequencies over which electromagnetic radiation extends.

Surfaces and radiation

Dark, matt surfaces are better emitters of thermal radiation than light shiny surfaces.

Dark, matt surfaces are better absorbers of thermal radiation than light shiny surfaces.

Thermal blankets have a light, shiny surface because it emits much less radiation than a dark matt surface.

Conduction

Conduction mainly occurs in solids. 

Most liquids and gasses are poor conductors.

Conduction in a metal is due mainly to free electrons transferring energy inside the metal.

Non-metals are poor conductors because they do not contain free electrons.

Materials such as fibreglass are good insulators

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