Multiple choice

The temperature does not decrease in a thermo flask because of

  1. vacuum

  2. vacuum and the silver coating on the inner walls

  3. the existence of a kind of gas between the walls

  4. silver coating on the outer walls
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A thermos flask prevents heat loss through conduction and convection using vacuum, and through radiation using silver coating on inner walls. The vacuum between the walls stops heat transfer by conduction and convection since both require matter. The silver coating reflects infrared radiation back into the flask, keeping contents hot or cold.

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