THERMOS
How is milk kept cold in a thermos?
what we call thermos, is a vacuum insulated bottle. This bottle works thanks to that they isolate everything that they put themselves in, that means that yes. you throw something cold, like milk, the bottle barely allows heat to enter. When you throw something hot, like chocolate, the bottle almost does not let heat get lost.
The thermos is a bottle inside another, between them there is a small space, from which almost all the air has been extracted. From a space in which there is no air or very little, it is said to be empty. The vacuum prevents the air from touching the inner bottle, it is very important that there is little air between both bottles, because the air transmits the cold and heat.
However, some heat can always pass through the vacuum, although much of it is blocked by the silver bath that covers the bottle. The heat, which travels by waves, bounces with the shiny and silver objects, and being glass the inner bottle also isolates, since glass is not a good conductor of heat.
Translation of my post https://steemit.com/busy/@alexander19/termo

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