Draw a neat labelled diagram of a thermos flask. How does it prevent transfer of heat by conduction, convection or radiation?

A thermos flask prevents prevent the transfer of heat by conduction, convection or radiation in the following ways:

(1) The vacuum between the rubber, two walls, cork, glass, and air does not allow the loss of heat by conduction.

(2) Cork in the neck of the flask and the cup over it prevents heat loss by convection.

(3) Because of the vacuum between the two walls, heat cannot be lost by conduction or convection.

(4) Heat loss is also minimised by radiation, by painting the outer surface of the inner wall and the inner surface of the outer wall with silver colour. Thus, the inner wall becomes a bad radiator and the outer wall becomes a good reflector of radiation.


Simply Easy Learning

Updated on: 10-Oct-2022


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