Final answer:
A thermos flask works by minimizing heat transfer through various parts such as the vacuum, silvering of the walls, thin-walled long glass neck, rubber support, air layer, and stopper. These parts reduce heat transfer through conduction, convection, and radiation to keep the contents of the flask hot or cold for an extended period.
Step-by-step explanation:
Working of a Thermos Flask
A thermos flask, also known as a Dewar flask, is designed to slow down all forms of heat transfer. It accomplishes this through various parts:
- Vacuum: The vacuum layer between the inner and outer walls of the flask prevents heat transfer through conduction and convection.
- Silvering of the walls: The inner walls of the flask are silvered to reflect heat radiation and minimize heat transfer through radiation.
- Thin-walled long glass neck: The thin-walled neck reduces heat transfer through conduction from the liquid contents to the outside.
- Rubber support: The rubber support helps to keep the flask intact and prevents heat transfer through conduction from the outer wall to the inner wall.
- Air layer: The air layer between the outer wall and the silvered inner wall acts as an additional insulator, reducing heat transfer through conduction and convection.
- Stopper: The stopper seals the flask, preventing heat transfer through convection and minimizing heat loss from the opening.