in which form of heat transfer is a medium not required?

係 phy 既問題呀,,,,請幫幫忙回答呀~~~

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  • 1 decade ago
    Best 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:

    輻射:是直接通過紅外線輻射向為發散熱量,傳導速度取決於熱源的絕對溫度,溫度越高,輻射越強

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