- This is the transfer of heat energy via electromagnetic radiation produced by heated surfaces
- Heat transfer via the process of radiation does not require a medium (solid, liquid or gas) for transfer - it can happen through a vacuum
Emitters and reflectors of radiation
When electromagnetic radiation strikes a surface, that energy is either absorbed or reflected. Good absorbers of radiation are good emitters of radiation.
The radiation that is not absorbed, is reflected so good absorbers are generally bad reflectors of radiation.
Factors affecting absorption and emission of radiation
- Texture of the surface (rough vs. smooth) - a smooth surface is a poor absorber and, by extension, a poor emitter of radiation. A smooth surface like a mirror is a good reflector of radiation.
- Nature of the surface (dull vs. shiny) - dull surfaces are great for absorbing radiation
- Colour of the surface (black vs. white) - darker colors are better as radiation absorbers
- Area of the surface (large surface vs. small surface) - larger surface allows for more radiation to be absorbed or reflected. If the other properties of the surface make it reflective then the surface will be a better reflector of radiation. The same goes for absorption of radiation.