Introduction: Solar ovens are metal boxes painted different colors. When you place these boxes in sunlight they will heat up to different temperatures. The hotter ovens are the ones that absorb more of the sunlight. The color of the boxes plays a role in the amount of heat absorption.

After discussing and learning about the light spectrum and light absorption your students should be able to accurately predict the outcome of this experiment before attempting it.

Materials:

• 5 - metal boxes. Overall size is not critical however, they must all be the same size and must be able to hold a thermometer. If metal boxes are unavailable you may substitute a cardboard box covered inside and outside with aluminum foil.
• 5 - thermometers. It is preferable that they measure in both Farenheit and Celsius but not essential.
• Pain - While, Black, Red, Blue, and Green
• Food items that will melt easily. The ingredients used to make S'mores work well.

Procedure:

• Paint the outside of five metal boxes.
• Place a thermometer inside each box.
• Place the food items inside each box.
• Place the ovens in direct sunlight for 15-20 minutes.
• Note: It is best to place the solar ovens on some insulating material such as wood.
• Record the starting and ending temperature for each solar oven.
• Calculate the temperature difference.
• Order the colors by their temperature change from coolest to hottest.
• Have students record their results. A variety of graphs may be used to show the results.

Results:

The coolest oven should have been the white one, and the black oven should have been the hottest. The white oven may have dropped in temperature by 1 degree Celsius. The black oven should have heated up by about 4 degrees Celsius over a 15 minute period. The green, blue and red ovens should have had an increase of about 3 degree Celsius.

In one controlled experiment the green oven got hotter than the black oven by 1 degree Celsius. Part of the difference may have been due to measurement accuracy of about 1-2 degrees Celsius. Because a color absorbs all colors of light except for its color, we expect that colored ovens will behave much like a black oven which absorbs all colors.