Question

what is thermos flask? give it's construction and working​

Answer 1

Answer:

• A vacuum flask is an insulating storage vessel that greatly lengthens the time over which its contents remain hotter or cooler than the flask's surroundings. Invented by Sir James Dewar in 1892, the vacuum flask consists of two flasks, placed one within the other and joined at the neck.

• It is constructed in such a way that heat loss due to conduction,convection and radiation is minimized. It is a double walled bottle of thin glass and the space between the walls is evacuated. ... The mouth of the bottle is closed by a cork or plastic stopper.

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Answer 2

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$\huge \color{orange}{ \fbox{Thermos Flask }}$

A thermos flask is a device that prevents transmission of heat by minimising these three process ( conduction, convection, radiation)

$\fbox \color{orange}{ Construction and Working }$

• It consists of a double - walled glass vessel, with vacuum between the two walls. So due to vacuum , no transfer of heat will take place by conduction through the double - walled flask.
• Heat loss due to convection is prevented by closing the mouth of the flask with an insulator like cork or plastic.
• Further, the sides of the double -walled flask facing each other are silvered. This prevents heat loss due to radiation, as shiny surfaces are bad absorbers and radiators of heat.
• The whole system is enveloped in a thick plastic or stainless steel case to prevent it from any damage.

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