Energy transfer by heating Flashcards
what is a conductor? what are some examples?
a material that allows electrons to flow freely from particle to particle.
metals
what is an insulator? what are some examples?
a material that restricts the flow of electrons from particle to particle.
wood, plastic
what happens during conduction
heat is transferred through vibrations of particles. as particles gain more energy they bump into nearby particles, transferring heat energy to them
what states does conduction happen in? which is the fastest and why?
it happens in all states of matter, its fastest in solids because particles are the closest together increasing frequency of collisions
why is conduction fastest in metals?
delocalised electrons can bump into ions throughout the whole metal, they can gain energy and transfer it further down the metal
what is convection
the transfer of heat energy through moving liquid or gas
what happens during convection
fluids near heat source gain energy and expand
this makes them less dense so they float to the top
cooler air replaces them forming a convection current until the whole fluid is heated
which states does convection happen in? why?
only liquids and gasses because it only happens in materials that can flow, solids are fixed.
what is evaporation
this is the change of state from a liquid to gas which occurs at boiling point
what is condensation
change of state from a gas to liquid
what happens in terms of energy during evaporation and condensation
during evaporation particles gain energy, allowing them to spread further
during condensation they lose energy
what is infrared radiation
heat transfer that can occur in vacuum
what 3 factors affect the rate at which a material transfers energy
- surface area and volume
- material of object
- heat source
dark, matt surfaces are ___ emitters and absorbers of infrared radiation
light, shiny surfaces are ___ emitters and absorbers of infrared radiation
good
bad
light, shiny surfaces are ___ reflectors of infrared radiation
good
