Question

How does a thermos flask minimise heat transfer?

Answer 1

1. The glass of the thermos flask itself is a bad conductor of heat.
2. The vacuum in between two glass walls prevents heat transfer by conduction and convection.
3. The silvered surfaces of the glass flask minimise heat transfer by radiation.
4. The insulating stopper and insulating padding between the flask and the outer container also prevent heat transfer.
5. As a result, hot liquid taken in the thermos flask remains hot and cold remains cold.