Heat Energy Flashcards
(14 cards)
What does the silvered glass and vacuum do?
Vacuum stops convection and silvered glass reflected thermal radiation
What is in a flask?
Silvered glass
Vacuum
What is convection?
When a liquid or gas is heated and then get less dense… This causes it to rise and then cools and drops because it is then more dense…
What is conduction?
When a solid is heated and the vibrations pass through the solid… The free electrons also transfer heat
What type of surfaces reflect heat?
White and shiny
What type of surfaces absorb heat?
Black and matte
What is thermal radiation?
Heat transfer through waves and can travel through a vacuum
Specific heat energy?
The energy needed to rise the temperate of a substance by 1oC
Water = 4200 J/KgoC
What is condensation?
The opposite of evaporation
Gas into a liquid - heat given to surrounding area… Works best on good conductors
What is sublimation?
When a solid directly converts to a vapour…
What are U-values?
Determines the quality of an insulator…
4 ways heat can be transferred?
Convection, conduction, radiation and change in state…
How can conduction be increased?
Use better conductive metal
Decrease thickness
Increase in surface area
Increase temperature difference
What is payback time?
The time it takes for you to save the amount of money you paid for the product… Eg double glazed windows
