Heat has three methods of transition, or transportation, however you want to look at it: Convection, conduction, and radiation. Convection is physically moving, like hot air rising. Conduction is like heating on a stove, the heat from the burner conducts to the pot to heat the food. Radiation is like the sun, you can feel it and see it.
Thermoses work by putting a vacuum or partial vacuum between the inside and the outside of the thermos. This makes it difficult for heat to conduct through matter within the vacuum, like air, since it's so sparse. The only conduction occurs through the bottom or top of the thermos where the inside and outside meet. This also makes convection difficult because there aren't many molecules in the lining to convect the heat. Radiation is reduced by using a reflective or white material. This tends to reflect radiation, whereas a dark color (black) would absorb it (You can see the difference by wearing a black or white shirt in direct sunlight and see which gets warmer).
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Convection is physically moving, like hot air rising. Conduction is like heating on a stove, the heat from the burner conducts to the pot to heat the food. Radiation is like the sun, you can feel it and see it.
Thermoses work by putting a vacuum or partial vacuum between the inside and the outside of the thermos. This makes it difficult for heat to conduct through matter within the vacuum, like air, since it's so sparse. The only conduction occurs through the bottom or top of the thermos where the inside and outside meet. This also makes convection difficult because there aren't many molecules in the lining to convect the heat. Radiation is reduced by using a reflective or white material. This tends to reflect radiation, whereas a dark color (black) would absorb it (You can see the difference by wearing a black or white shirt in direct sunlight and see which gets warmer).
And yes, I even reads this though.
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