Why thermos flask does not let the heat escape?

Answer 1

It is especially designed to reduce heat transfer through conduction, convection, and radiation. A vacuum between two layers reduces the heat transfer through conduction and convection; the fact that the surfaces are mirror-coated also reduces losses through radiation.

Answer 2

this is mainly a physics qns on heat transfer. heat can be lost in 3 ways, conduction, convection and radiation. conduction is heat transferred via contact with a solid, convection is heat transfer through liquids or air and radiation is heat transfer via energy (mainly infra-red).

A thermos flask is made to reduce heat loss via each of the 3 above mentioned ways of heat transfer. if u can obtain the image of a normal thermos flask, the 1st thing u can see is that the body and cap of the flask is hollow. this hollow area is actually vacuum, meaning it's empty, not even air occupies it. while this minimizes heat loss via convection and conduction, this however does not prevent heat loss via radiation since energy doesn't require a medium to travel. now if u open up the thermos flask n look at the interior, u realize it's a mirrored surface. based on the physics text, shiny and silver surfaces absorbs and radiates heat poorly. this is why the interior surface is shiny and is silver. this usually is on both sides of the hollow area (vacuum) of the thermos flask.

with a combination of these factors, this is why a thermos flask is able to retain heat for extended periods of time.

Answer 3

A thermos flask has a double-walled design with a vacuum between the walls that acts as a thermal insulator. This vacuum prevents heat transfer by conduction or convection, while the reflective coating on the inner wall minimizes radiation. As a result, the heat is trapped inside the flask, keeping hot liquids hot and cold liquids cold for extended periods of time.