Insulation To understand how insulation works. Double Glazing Which of the statements about the...
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Transcript of Insulation To understand how insulation works. Double Glazing Which of the statements about the...
InsulationInsulation
To understand how insulation works
Double GlazingDouble Glazing
Which of the statements about the double glazing are true?
Our windows will keep heat in the home
Heat energy easily escapes from the window
Radiation can pass through the gap
Conduction can take place through the gap
Convection can take place through the gap
Conduction cannot take place through the gap
Convection cannot take place through the gap
Heat energy can reflect back into the house
Double GlazingDouble Glazing
The true statements about the double glazing were: - Radiation can pass through the gap Conduction cannot take place through the gap Convection cannot take place through the gap Heat energy can reflect back into the house Being semi-reflective light can enter, but some heat
energy is retained in the home, being reflected back in
RadiationRadiation
Your task is to design an experiment which can keep 200ml of boiling water as hot as possible for as long as possible
Teams will be out when their water drops by 10ºC
The team which has their water above 90ºC for the longest will be the winner…
Radiation ExperimentRadiation Experiment
This experiment consists of the following rules: -
You may only use 4 of the following items: glass beaker; tin beaker; plastic beaker; bubble wrap; foil; cotton wool; black paper; white paper; wool; and cardboard
You may only use 1 piece of each of the above
You must use 200ml of boiled water
The winner is the team whose flask takes the longest to drop 10ºC
Draw and label your design – make sure you label the 4 pieces of equipment you have chosen and why
ResultsResults
Can you explain your findings: - Which set-up resulted in the temperature staying high for the
longest? What has the colour got to do with the temperature transfer? What did the cotton wool / bubble wrap do etc…
All objects continually emit / absorb thermal radiation
A hot object emits more heat radiation than it absorbs (cooling down)
A cold object emits less heat radiation that it absorbs (warming up)
Heat TransferHeat Transfer
Something which slows down the rate of heat transfer is called an insulator
If you can reduce the amount of conduction, convection and radiation then the amount of heat transfer will be reduced, keeping the water’s high temperature for longer
The plastic beaker works as an insulator, not allowing convection to take place between the liquid and the solid plastic beaker
The tin foil is poor at emitting infra-red radiation, so not much energy is transferred through the foil (it reflects back)
The bubble wrap is good insulator as the bubbles of air reduce the amount of conduction which can take place
The cotton wool is also a good insulator, reducing the amount of conduction which can take place (lots of air spaces)
CoolingCooling
Look at the following experiment – write a conclusion for the results with as much scientific knowledge as possible…
Time (mins)
Temperature (°C)
A B C D
0 90 90 90 90
2 85 87 88 89
4 81 85 86 88
6 78 82 84 86
8 74 80 82 85
10 70 78 79 83
ConclusionsConclusions
Tube A – uncovered tube loses heat quickest – heat is radiated from the tube more readily
Tube B – aluminum foil results in less heat loss – some heat is reflected back into the tube
Tube C – fibre glass wool retains most heat – glass fibre seems to be a better insulator
Tube D – covered with glass fibre wool + aluminum foil on the outside is the best arrangement for insulation, combining the properties of both