heat transfer Flashcards
name three types of heat transfer
ConvectionConductionRadiation
What is RADIATION
radiation is the heat energy emitted (given off) by an object
name the main source of radiation
the sun
name three things that emit heat radiation
firekettlehumanstoastercookerthe list is huge!!!!
how does the radiation from the sun help us
it provides daylightit provides warmth for our planetwe can capture the suns energy (solar energy) and turn it into electricity
a dark coloured surface absorbs radiation better than a light surface true or false
true - a dark surface absorbs more energy than a light one
a shiny surface absorbs radiation better than a matt surface true or false
False - a matt surface absorbs more energy
which reflects more energy a shiny surface or a matt surface
a shiny surface
does a smooth surface absorb/reflect more energy than a bumpy surface
yes the bumpy surface has a larger surface area to absorb/reflect energy
what do we mean by the term CONDUCTION
conduction is where heat energy is passed from atom to another
plastic and wood are good conductorstrue or false
False - plastic and wood are poor conductors of heat
are metals good conductors of heat
Yes - a metal rod heated at one end will eventually get hot at the other end
why do pans and cooking equipment have plastic or wooden handles
to stop you from burning your fingers and hands. the wood and plastic does not conduct the heat from the pan to your hand
why are pans made of metal
so that the pan conducts heat from the cooker to the food
what does CONVECTION mean
convection is the process where hot fluids rise and cold fluids fall
does convection take place in solids liquids or gases
it happens in liquids and gases where the molecules are able to move
how does convection work
in a pan of water on a cooker the water near the heat (the bottom) warms up and moves to the top of the pan.cold water moves in behind it and gets warm. this produces a convection current
how do we use convection in our homes
to heat the air in our rooms - the radiator or fire warms the air which rises and then cold air moves in behind and gets warmed upto heat our waterto cook foodto boil the kettle
what do we mean by the term insulator
this is something we use to prevent heat loss from a heat source
name some ways we use insulation
to stop heat loss from the roof - loft insulationto stop hot liquids from cooling too quickly - flaskto stop cold liquids getting hot - flaskto stop heat loss from the walls - cavity wall insulation
