Physics Solar cooker

1. Physics Solar cooker

2. Table of Contents Introduction of solar cooker……………………………………P.1 Principles of solar cooker……………………………………P.2-3 Processes of making a solar cooker…………………………P.4-6 Introduction of our solar cooker……………………………P.7-8 Conclusion ………………………………………………P.9-10

3. Introduction of solar cooker Solar cookers, as their name implies, use the sun as their energy source.  As long as the sun is shining (even with cloud cover!) they allow for free, convenient, safe and smokeless cooking.  As with any cooking appliance, various models are suited to various dishes and with over 200 models to choose from, one has to make sure you purchase the brand of cooker suited to your cooking requirements. P.1

4. Principle of solar cooker The light energy that is absorbed by dark pots and the dark absorber plate underneath the pots is converted into longer wavelength heat energy and radiates from the interior materials. Most of this radiant energy, because of having a longer wavelength, cannot pass through the glass cover and escape, and is therefore trapped within the enclosed space. Critical to solar cooker performance, the heat that is collected by the dark metal absorber plate and pots is conducted through those materials to heat and cook the food. P.2

5. Glass orientation:  The more directly the glass faces the sun, the greater the solar heat gain. Although the glass is of the same size for box 1 and box 2, more sun shines through the glass on box 2 because it faces the sun more directly. Note that box 2 also has more wall area through which to lose heat. Reflectors, additional gain:  Single or multiple reflectors bounce additional sunlight through the glass and into the solar box. This additional input of solar energy results in higher cooker temperatures. P.3

6. Processes of making a solar cooker First, we need to prepare a piece of black paper, aluminium foil, a can and an adhesive paper. Then, we cut a circle and a rectangle from the black paper. P.4

7. And then, we fix the circle and rectangle together (as shown in the picture). We can also put some aluminium foil in the circle tins.It can reduce the heat energy loss by radiation. Then we put some water in the cans.And put a thermonmeter in the cans to test what temperature the water rises. And we will paint the surface of the cans be black in colour.It can reduce energy loss by conduction P.5

8. This is our finish product. We use some wrap paper to covr the solar cooker,It can make the solar cooker like a green house.We can use the principle of green house effect to make the solar cooker.Green house effect can use in our daily life.For example ,some farmers will use this principle to grow plants. P.6

9. Introduction of our solar cooker This is our design of a solar cooker.First we use some black paper to make the body of the solar cooker,black colour is a good absorb of heat energy,it can absorb more heat energy into the solar cooker. Second we put some aluminium foil into the solar cooker, aluminium foil is sliver in colour .It will reflect sun light energy away and then it can reduce heatenergy loss by radiation. P.7

10. We also put make a cover on the top of the solar cooker.The cover is made up of wrap paper ,it is colourless.So that it can allow more sun light pass though the solar cooker.AS it can make a principle of green house effect.What is a green house effect? The atmosphere of the earth acts in a very similar way to a greenhouse. Sunlight penetrates through the transparent air and causes the ground to warm. The atmosphere then acts as a blanket, keeping the warmth of the Earth from escaping back into space. This effect is due to certain gases in the atmosphere which are very good at absorbing the heat energy before it is lost to space. P.8

11. Conclusion Yiu Hiu Chi: This topic is about making solar cooker.When we first to make the solar cooker.We had faced some of problems, such as what type of material we should choose that could make the setting more better.We also needed to design a model that can absorb more sunlight to make the water temperature rise up.As the result,although our solar cooker was not success. Nonetheless,I think this can be my experience.We can do better afterward. Choi Ka Shing: I think this is a good chance to practice our physics concept. When we doing this experiment ,I can learn how to use physics principle to make a solar cooker.For example,we use black paper to make our solar cooker,black colour is a good absorber of heat energy, so that it can absorb more sun light energy for raise the water’s temperature.So I can learn more about how to use physicsprinciple in our daily life. p.9

12. Ng Chi Shing: This solar cooker project is very useful to absorb the light energy to cook the water.Although our solarcook is not the best one to heat up the temperature in the class,we also have done our best during the project.During the making solarcooker, I learnt how absorb to heat the water and knew that there are many problems to effect the temperature.Such as the changing of environment,the site of the solarcooker.So that heat up the water is very difficult. Lee Kwong Sum :I learn something about heat principle and application of making a solar cooker.When we do the experiment ,the aluminiu8m foil can not cover all the solar cooker,therefore some energy may loss by conduction,it will affect our experiment result.It is a common mistake.We use wrap paper to cover the top of the solar cooker,it can reduce the energy loss by conduction or convection. p.10

13. Our group members • Choi Ka Shing4C(24) • Lee Kwong Sum4C(32) • Ng Chi Shing4C(36) • Yiu Hiu Chi4C(39)

14. The End Thank You For Your Attention