in which form of heat transfer is a medium not required?
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- myisland8132Lv 71 decade agoBest Answer
Radiation does not require medium
Radiation is transfer of heat through electromagnetic radiation in the heat spectrum. Hot or cold, all objects radiate heat—unless they are at absolute zero, which is unattainable. No medium is necessary for radiation to occur; radiation works even in and through a perfect vacuum. A prime example of this is heat from the Sun, necessary for life on earth, which travels through the vacuum of space before warming the earth.
"Shiny" materials typically reflect radiant heat, just as they reflect visible light; dark materials typically absorb heat, just as they absorb visible light. In actuality, light is another a form of electromagnetic radiation with a shorter wavelength (and therefore a higher frequency) than heat radiation. The difference between visible light and radiant heat is small: they are simply different "colors" of electromagnetic radiation.
2006-10-26 04:18:03 補充：