Insulation Flashcards
Define thermal insulator
A thermal insulator is a material with a low thermal conductivity
What does insulation do
Insulation prevents heat loss from an object, therefore keeping the object warmer
State the various types of insulation used in our homes to prevent heat loss
Double-glazed windows
Cavity wall insulation
Loft insulation
Carpets
Aluminium foil behind radiators
External walls with thicker bricks and lower thermal conductivity
How does double glazed, cavity wall insulation, loft insulation and carpets prevent heat loss
They use trapped air to prevent heat loss. The materials trap air particles, air is a very poor conductor of heat and therefore heat loss by conduction is reduced
How does aluminium foil behind radiators prevent heat loss.
The shiny foil will reflect the infra-red radiation back to the radiator so it is not absorbed by the wall keeping the room warmer.
how the rate of cooling of a building is affected by the thickness and thermal conductivity of its
walls.
Thick walls with a low thermal conductivity reduce the rate of thermal energy transfer (by conduction) from the inside of the building to the outside. Which also reduces the cost for heating.
Can you stop heat loss
You cannot stop heat loss, you can only slow it down
Complete the sentence
Heat is always lost from a house, insulation _______ down the process of heat loss.
Complete the sentence
Heat is always lost from a house, insulation slows down the process of heat loss.
What would eventually happen to a house if the heating remains off
Eventually a house will be at the same temperature as the outside, if the heating remains off
When does heat transfer stop
Heat transfer stops when the temperature of the two objects interacting are the same
State the features of the design of a vacuum flask keeps the inside liquid hot/cold
Plastic cap
Double-walled plastic container
Inside silvered surfaces
vacuum
Double-walled glass container
Describe how the design of a vacuum flask keep the liquid inside hot
The plastic cap is a good insulator therefore stops heat escaping from the container by convection
A vacuum does not contain any particles. This stops heat loss by conduction and convection
The silvered surfaces will reduce the emission of infra-red radiation and reflect infrared radiation back to the hot liquid
The double walled container is made of glass and glass is a poor conductor of heat
How will the sheet of shiny metal foil help to stop heat going back into the fridge
The black metal pipe emits infra-red radiation, the shiny meal foil reflects this to stop it going back into the fridge
Why is the part of the pipe outside the fridge painted matt black
Matt black is the best emitter of infra-red radiation
What effect will the coolant have on the air around the outside of the fridge
It will heat up the air and the surroundings.
