Question

Which of the following is an insulating component in thermos flask?

• A. plastic foam
• B. air
• C. vacuum
• D. All of the above

Answer 1

The correct option is D All of the above

Insulating component in thermos flask are plastic foam, air, vacuum.

As plastic foam is insulator, so to prevent heat to radiate plastic foam is used just after the inner layer, plastic foam is being polished to reflect the inner heat inside, as air is bad conductor of heat it does not conduct heat just outside the outer layer. Vacuum is poor conductor of heat. It is situated between two layers, which prevents heat conduction through convection.