A Study of the Absorption and Reflection of Solar Energy When Applied to Different Colors

ABSTRACT


The major idea that we state in our hypothesis is that if an object is a darker color, then it will absorb more heat than a lighter colored object will. It also states that if an object is a lighter color, then it will reflect more heat than a darker color.

In order to find out if our hypothesis is true, we had to conduct an experiment. In our experiment we placed a thermometer inside a box. We used four different boxes of different colors, red, yellow, white, and black. The boxes had holes in the top and the walls of the box were to either absorb or reflect heat. We have tested this experiment many times and each time we have proved our hypothesis correct. Each time the darker color absorbed more heat and the thermometer proved that this had happened. And the thermometer also proved that the lighter color reflected more heat because the temperature was lower.

Even though many scientists have done this experiment and proved that what we stated in our hypothesis was true, we still wanted to prove to ourselves that what we stated was a fact, and we also wanted to know to what extent the color of an object affected its ability to absorb or reflect solar energy.



I. STATEMENT OF PURPOSE AND HYPOTHESIS


We are doing our Physical Science Research Paper on How the Color of an Object Affects its Reflection and Absorption of Solar Energy. We think we have all heard from time to time about how darker colored objects absorb more heat than white or lighter colored objects do. On hot days you have probably been told that it would be wise to wear a white shirt to keep you cool. Having heard things like this our whole lives, we thought it would be interesting to find out for ourselves whether the concept is true and if it is true how much effect the color of the object has on its absorption or reflection of heat and solar energy.

According to the research we have already done, we based our hypothesis on the statements that solar energy is better absorbed by darker colors. We cannot be completely sure about this, but after tests we will find out the truth. This is our hypothesis: If solar energy is applied to two different colors, the darker of the two will absorb more heat.



II. REVIEW OF LITERATURE


Energy needed to operate today’s technological society might be supplied in a number of different forms including fossil fuels, nuclear energy, and solar energy. Because fossil fuels and nuclear energy tend to contaminate and pollute the environment, much research is being done on how to effectively and economically make use of solar or radiant energy. (Daniel, 1999). Solar energy is energy that comes from within the sun, which is a big ball of gas made up mostly of hydrogen and helium (Colorado Education, 2000).

People began using solar energy as early as the 7th century B.C. when they used magnifying glasses to concentrate the light of the sun to make wood catch fire. The first time solar energy was harnessed was when a French scientist used heat from a solar collector to make steam to drive a steam engine. This all took place about 50 years after the American Revolution, which was in 1776(Scanlon, 2000). It was not until the beginning of this century that scientists and engineers really became serious about developing ways to use solar energy (Colorado Education, 2000). When the space program began to become important in the 1950’s, the silicon-based solar cell was developed and from that, the solar panel collector was developed (Scanlon, 2000). In order to use solar energy efficiently, it is necessary to have a solar collector, which is a device which allows sunlight inside, absorbs the sunlight and changes it to heat, and then traps the heat inside. The efficiency of a solar collector depends on the time of day, the season of the year, the latitude of the area, weather conditions, and the color of the collector (Colorado Education, 2000).

There is a direct relationship between the amount of heat absorbed by a solar collector and the color of the collector. Dark colors absorb more heat than light colors, and shiny colors reflect away from the collector. The study of colors and absorption of energy has become an important issue in the past ten years because energy efficiency is affected by this absorption. President Clinton developed a Climate Change Action Plan which was designed to cut the nation’s energy use 20 percent by the year 2000. A major part of the plan dealt with the use of light and dark to change cities into cooler places that needed less energy to cool. Rising fossil fuel prices should be an incentive to people to begin to build and design housing and buildings with lighter colored roofs which would be more cost efficient to cool (Wooldridge, 1994).



III. METHODOLOGY


Materials:

  1. Four boxes of approximately the same size
  2. Four outdoor thermometers
  3. One Pocket Knife/Scissors etc.
  4. Four sheets of any kind of clear wrap
  5. One roll of clear packaging tape
  6. Four cans of spray-paint of different colors.
  7. Preferred: One black one white and two intermediate colors



Procedure:

1. Take each of the four boxes and cut a rectangular shaped hole in the top. Make sure that each of your holes are the same shape and size, the sunlight will be collected through this whole.

2. Take each of your boxes and spray-paint them different colors, make sure you get the inside and the top of the box good. Let boxes sit for at least 30 minutes in order for them to dry.

3. Place each of the thermometers inside the boxes with the scale faces upwards. Make sure when you do this that they all read the same temperature.

4. Take the clear saran wrap or other clear cover and place it over the hole you cut into the top of the box. Tape or glue the wrap to the box.

5. Now take your packaging tape or any other clear tape and tape the edges of the box and any holes or gaps where heat could possibly escape.

6. The last step is to place the boxes, with the thermometers inside, out in the sun. Every 10 or 15 minutes check the temperature on the thermometers and record them individually on a chart.



IV. ANALYSIS OF DATA


If you look at the data recorded you will see that it clearly shows truth in our original hypothesis. You can see that the different colors of a material affect its ability to absorb and reflect solar energy. Looking at our data and the chart you can tell that the darker the colors (black and red) showed a steady rise in temperature, and in the lighter colors (white and yellow) the temperature remained more constant.

We performed tests on three different days. Our results varied a little but it was still evident that the temperature increased in the black box more than in the white and yellow boxes. The pictures and charts on the following pages show results that coincide with our original hypothesis.

Charts for Day 1,Charts for Day 2,Charts for Day 3.


V. DISCUSSION

After performing many tests and studying our topic for weeks we have now concluded that the color of an object does affect its ability to absorb or reflect solar energy. Our tests were conclusive in proving that darker colors will absorb more solar heat than lighter colors over the same period of time. After three separate days of testing our experiment, we came out with the same results, that dark colors do absorb more heat.

If we could take this knowledge of the reflection and absorption of solar energy and use it in our everyday lives it would make many choices easier. For example: what to wear on cold or warm days, how to insulate our homes, what color roof to put on our houses, and many other things. This knowledge could make our lives much easier and it would lower many expenses.

Reference List


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