Name: Thermos Flask: Construction and Working
Uploaded: 2019-07-19
Duration: 3 min 30 s
Description: The thermos flask is the most commonly used liquid container during the winter season. Watch the video to learn the principle based on which the thermos flas...

Question

Draw a labelled diagram of a thermos flask. Describe its working.

Accepted Answer

The thermos flask is a special type of bottle or flask which keeps hot liquids hot and cold liquids cold for a long time.

Working: A thermos flask is designed to reduce the gain or loss of heat by conduction, convection, or radiation. The thermos flask works as follows:
• The vacuum between the double walls of the flask prevents heat transfer by conduction or convection.
• Glass, cork, and rubber are bad conductors of heat due to which heat neither escapes from within nor enters from the outside.
• The brightly polished walls of glass minimise heat transfer by radiation.
• Thus, heat transfer by all the three modes of transmission is minimised and the temperature of the liquid inside the flask is maintained for a longer time.

Draw a labelled diagram of a thermos flask. Describe its working.

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