polyethylene Clean wrap(cover the solar cooker)

Silvery paper(in side the solar cooker)

Black tape

Wood pick

Magnifying glass

Application of physics principle ●The solar cooker is mainly made by polyethylene which is a good insulator of heat, it can reduce heat loss to the surroundings by conduction.

●The solar cooker is covered by Clean Wrap. It allows radiation from sun to pass through. The radiations entering the solar cooker warm up the air. The warm air re-emits infra-red radiation, but this radiation cannot easily escape through the clean wrap and is trapped inside the solar cooker. Therefore, it keep the solar cooker warm and can have temperature rise easily.

●For the inner surface of our solar cooker, it is surrounded by silvery paper, which is a poor radiator of heat, so it can reflect the energy in the solar cooker many times. Therefore, the temperature in the solar cooker can rise rapidly.

Application of physics principle

● The can is surrounded by black tape, which is a good absorber of heat. Therefore the can can absorb heat energy from the solar cooker much easier. And the air is trapped between the can and the black tape, therefore it can reduce heat loss to the surroundings by conduction.●The solar cooker covering by clean wrap can also prevent heat loss to the surroundings by convection.

Application of physics principle●We remove the cover of the can so that there is a larger surface area to absorb energy. Thus, water can absorb more energy.

●There is a magnifying glass placed above the can. This is used to focus the light and heat energy onto the can of water, therefore the water can absorb energy more efficiently.

1Temperature taking 1

We took the temperature per 5 minutes for 1 hour. It rose from 27oC to 43oC in an hour. The average temperature rose was 1.33oC / 5mins.

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1

We took the temperature per 5 minutes for 55 minutes. It rose from 23oC to 48oC in an hour. The average temperature rose was 2.27oC / 5mins.

2Temperature taking 2

2

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Time(MINS)

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(*C)

Conclusion &Discussion

Through the reflection of light (by pasting the shiny silvery aluminium foil onto the inner surface of the solar cooker), we can reflect the light onto the middle of the solar cooker.

Also,using the magnifying glass, we can focus the light to heat up the can of water.

Using polystyrene to construct the body of solar cooker, we can decrease the heat loss to the surrounding through conduction.

To reduce the heat loss by convection, we reduce the volume of the solar cooker so that the amount of the air inside it will be smaller.

To enhance solar energy absorption by radiation, we make use of greenhouse effect. We cover a piece of transparent wrap on the upper part of the solar cooker.Also,we painted the container of water black to absorb more energy by radiation.

Finally, to enhance our solar cooker's performance, we suggest to hold this activity in the afternoon. Since sunlight will be stronger in the afternoon. In addition, we suggestto face the water directly to the sunlight that it can absorb the maximum amount of energy.