Solar Cooker Project
by 1A Group 2
Group Members, Duty List and Contributions
Chan Jie Ying, Jolene (2) → construction of solar cooker, temperature-taker, data analysis, compilation, video filming, video editing, creation of flyer, flyer editor
Lee Wen Xuan, Shalyn (10) → construction of solar cooker, water-measurer, video editing, creation of flyer, final video editor
Tay Yi Ting (18) → construction of solar cooker, materials-seeker, data analysis, compilation, video filming, video editing, creation of flyer, flyer editor, overall final editor
Khoo Zheng Xin Charmian (26) → time-keeper
Components of an Experimental Design
Title: To investigate the effect of the area of exposed surface area of water on the increase in the temperature of the water.
Hypothesis: The larger the exposed surface area of the water, the higher the increase in temperature of the water.
Independent variable: exposed surface area of the containers
Dependent variable: increase in temperature of the water
Constants: temperature of water at the start of the experiment, type of water, material of containers, volume of water, the surrounding temperature where the experiment is conducted
Number of Trials: 3 × 5 = 15
Materials Used To Build The Solar Cooker
- 1 shoe box
- 1 penknife
- 1 piece of aluminium foil
- clear tape
- 2 layers of plastic wrap
- 1 layer of black colour paper
- chopstick (break into half)
Method Of Building The Solar Cooker
- Use the penknife to cut a flap in the lid of the shoe box. Cut along three sides, leaving about 1 inch between the sides of the flap and the edges of the lid. Fold this flap out so that it stands up when the box lid is closed.
- Cover the inner side of the flap with aluminum foil so that it will reflect rays from the sun. To do this, tightly wrap foil around the flap, then tape it to the back, or outer side of the flap.
- Use clear plastic wrap to create an airtight window for sunlight to enter into the box. Do this by opening the box and taping 2 layers of plastic wrap over the opening you made when you cut the flap in the lid. Leave about 1 inch of plastic overlap around the sides and tape each side down securely, sealing out air.
- Line the inner surface of the box with black colour paper - black absorbs heat. The black surface is where the water will be set to gain heat.
- The best hours to set up the solar cooker is when the sun is high overhead - from 11 am to 3 pm. Take it outside to a sunny spot and adjust the flap until the most sunlight possible is reflecting off the aluminum foil and onto the plastic-covered window. Use the chopstick to prop the flap at the right angle.
Photos of the Solar Cooker Construction
Method Of Conducting The Experiment
- Find a sunny place in an open area to place the solar cooker. (refer to step 5 of method of building the solar cooker)
- Label the containers A to E in ascending order of exposed surface area.
- Using the measuring cylinder, measure 40ml of distilled water.
- Record the temperature of the water using a thermometer.
- Pour the water into Container A.
- Place Container A into the solar cooker and cover the lid.
- Leave Container A in the solar cooker for 10 minutes.
- After 10 minutes, remove Container A from the solar cooker and record the temperature of the water.
- Repeat Steps 3 to 8 for containers B to E.
- Repeat the experiment for each container 2 more times. (Repeating the experiment a few more times enables us to have a more accurate and reliable result)
- Find the mean change in temperature for each container.
- Record the data in a table.
Photos of how we conducted the experiment
Repeat the experiment 3 times for each container, A to E.
Video Of How We Conducted The Experiment
Analysis and Discussion
What can you conclude based on the experimental results? Does the experimental results reject/ do not reject your hypothesis?
The larger the exposed surface area of water, the higher the temperature of the water in the same period of time. The experimental results do not reject our hypothesis.
What are the possible scientific explanations for these results?
Smaller/thinner bodies of animals have a larger surface area to volume ratio and their bodies gain and lose heat out of the surface of their body; more surface area means greater gains and losses. Bodies retain heat within their bodies; more volume means more heat retention. When the surface area is large compared to the volume (small/thin things), heat is gained and lost quickly because there is lots of surface area to gain and lose heat and relatively little volume to retain heat. Just like animals, the water with a larger surface area gains heat faster than that of a smaller surface area. Therefore we say that the larger the exposed surface area of water, the higher the temperature of the water in the same period of time.
How can you modify the procedure further to improve accuracy or reliability of the experiment?
- Change all the containers to opaque containers of the same colour and repeat the experiment 3 more times for each container.
- Conduct the experiment for a longer period of time.
- Repeat the experiment a few more times.
4. Add a control set-up (container A that is not in the solar cooker) to the experiment.
5. Add a layer of oil over the water in each beaker.
- Containers A, C, D and E are transparent and Container B is opaque and white in colour. The water in container B might gain heat at a slower rate as white colour reflects heat from the sun whereas the water in containers A, C, D and E might gain heat at a faster rate as containers A, C, D and E are transparent and allow most light and heat to pass through.
- Increasing the duration of the experiment will allow the water to gain more heat. There will be a greater change in the temperature of water at the end of the experiment it will be easier to compare the change of temperature of water.
- Repeating the experiment more times will reduce human errors and give a more precise result.
- This allows us to prove that the solar cooker is working and the container of water without the solar cooker gains less heat than that with a solar cooker.
- Since a larger surface area increases the rate of evaporation and a smaller volume of water gains heat faster, the opened containers will cause inaccuracy in the test results as evaporation can take place. In order to prevent this from happening, we can put a layer of oil over the water in each container to prevent evaporation from taking place, thus allowing a more accurate and reliable result.