Table of Contents
How does the vacuum flask resist heat transfer from radiation?
A vacuum flask, or thermos, does not allow heat transfer by any of the three ways that heat can travel. The silver coating on the inner bottle prevents heat transfer by radiation, and the vacuum between its double wall prevents heat moving by convection.
How the vacuum flask reduces heat loss by conduction and convection?
Hint: A vacuum flask or thermos flask is designed so that any means of conduction or radiation will not allow heat loss. The vacuum prevents conduction heat loss because the vacuum is a bad heat conductor. Because it is tightly sealed, the stopper prevents heat loss through convection.
How does a thermos flask prevent conduction convection and radiation?
Hint: A vacuum flask or thermos flask is designed so that it will not allow heat loss by any means of conduction or radiation. The vacuum prevents the heat loss by conduction because vacuum is a bad conductor of heat. The stopper prevents the heat loss by convection because it is tightly sealed.
What kind of heat transfer can happen in a vacuum?
Neither of those two work in empty space. But radiation — heat transfer via electromagnetic waves — can occur across a vacuum.
Why do silvered surfaces reduce heat loss?
Silvered surfaces reduce heat loss by radiation because silver is a poor radiator of heat. If the top is not covered, water conducts heat to the air and hot air rises as it is less dense than the cold air outside the flask, and heat is lost by convection.
Why is thermos flask silvered?
Therefore, the silver coating on the inner bottle of a thermos flask is used to prevent heat transfer by radiation and option (c) is correct. Note: The silver coating reflects the heat inside the thermos so that radiation heat transfer cannot take place.
How does thermos flask keep things cold or hot?
A thermos is a bottle with a double-walled container inside of it. The air between the two walls is sucked out during construction, creating a vacuum. The same vacuum that keeps hot things hot keeps cold things cold.