A thermos flask is polished well

Answer the following question orally: Why thermos flask is called Dewar flask?

When a thermos flask with some water in it is vigorously shaken. Does its temperature rise. Has some heat added to water during the process.

A well stoppered thermos flask contains some ice cubes. This is an example of

A well stoppered thermos flask contains some ice cube. This is an example of

Hot water in a thermos flask is an example of ____ system

The silvering in thermos flasks is done to avoid heat transfer by: