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