# Solar Heating Fact Sheet

Sunlight, which is a form of energy, is converted to heat when it is absorbed.

Light is composed of many colors classified by its wavelength. One way to remember the colors of the rainbow is the name "ROY G. BIV" for the colors Red, Orange, Yellow, Green, Blue, Indigo, and Violet. A sequence of colors is a called a spectrum. Besides the visible colors that we can see in a rainbow, "light" has many other wavelengths with names such as x-rays, ultraviolet, infrared, microwave, and radio waves.

The color from objects is caused by reflected light. That is, a red object appears red because it absorbs all colors but red. White and black are special colors. A white object reflects all colors. A black object absorps all colors. Therefore, black objects will heat faster than white objects when they are in the sunlight.

# Solar Oven Experiment

Introduction: The solar ovens are metal boxes painted different colors. These boxes, when placed in sunlight, will heat up to different temperatures. The hotter ovens are the ones that absorb more of the sunlight.

Procedure: The outside of several metal boxes are painted different colors. A thermometer, and optionally food like S'mores, are placed inside the oven. The ovens are placed into direct sunlight for a period of 15-30 minutes. It is best to place the solar ovens on an insulator like 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.

# Solar Oven Results

### Bear Creek 3rd Grades - 4/28/98 Martin Park and High Peaks 3rd Grades - 4/29/98

As students predicted, the coolest oven was white, and the hottest oven was black. The white oven actually dropped in temperature by 1 degree Celsius for one class. The black oven heated up by about 4 degrees Celsius over a 15 minute period. The green, blue and red ovens had an increase of about 3 degree Celsius. For one class the green oven got hotter than the black oven by 1 degree Celsius. Part of the difference is related to measurement accuracy of about 1-2 degree Celsius. Because a color absorbs all colors of light except for its color, we expect that colored ovens should behave much like a black oven which absorbs all colors.