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How Does A Vacuum Flask Work?

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A vacuum flask is a type of flask that aims to stop all three forms of heat transfer. Conduction, convection and radiation.
A vacuum flask prevents conduction by making a vacuum between the inside and the outside layer of the flask, so that the only solids that touch are the lid and the main body of the flask. This means the amount of conduction that occurs is minimised. One major drawback though, is when the hot water transfers heat with the cold air inside the flask, then the hot air transfers heat with the cold lid, and then on the likely chance that the lid is hotter than the surroundings, the lid transfers heat with the air molecules around it. This means that a considerable amount of heat is lost to the surroundings.
The only way convection can occur is by the hot liquid or solid transferring heat with the trapped air inside the flask, although this only affects the temperature of the water by a bit, because most of the liquid condenses again.
The flask is made so that radiation is reflected back of the sides, which is made of a shiny material. Also, the flask is not transparent; it is made of an opaque material, usually plastic or metal. The only way radiation can escape, is by the lid being taken off.
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The vacuum flask stops the liquids temperature from changing. It is made of a shiny surface so radiation is reflected away when they come meet in contact. The vacuum flask aims to stop all sorts of heat transfer such as conduction, convection and radiation. It is made of glass and metal.
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Muddassar Memon answered
A vacuum flask basically is a container which keeps the matter available in it, hotter or cooler than their surroundings by inserting an evacuated region to supply thermal insulation amid the contents and the environment.

A vacuum flask basically is a bottle which is made from glass, metal or plastic material having hollow walls in them. The thin section amid the internal and external wall is evacuated of air. The vacuum flask was created in the year 1892 by well known chemist James Dewar. The vacuum flask is also at times referred to as the Dewar flask.

The vacuum usually conducts heat via the method of radiation and radiative heat loss can be reduced by putting a reflective coating to the outer section.
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Anonymous answered
A vacuum has no particles of any kind this reduces the heat transfer by conduction and convection.
The shiny silver surfaces reflect infrared radiation.
The stopper is made of an insulator so heat energy is not transferred by conduction. It also stops convection transferring to or from our room.
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Magic

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A vacuum flask keeps your hot drink hot and your cold drink cold.
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I love thermos fflasks and you can't tell me I don't so shut the hell up I love thermos fflasks I like the hot stuff in them they keep me warm mmmmmmmmmmmmmmmmm
thanked the writer.
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Anonymous commented
Grand mums n babies live a hapi life bcoz of thermos flasks.............with them life is easier for them!!!!!!!!!!!!!!!!

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