Color & Heat Absorption
This is a compilation of information from students who are conducting scientific color experiments about color and heat absorption.
Questions:
#1 - I am doing a science fair experiment on color vs. heat absorption. I need ideas on research.
#2 - When using a thermometer, is it better to use cloth or construction paper?
#3 - Is it better to use a light source or the sun? Ben Franklin's research with cloth and snow sounds interesting. Has anyone tried to set that one up?
Best Scientific Answers
Color and Heat Absorption - from "Ask a scientist"
Color and Heat Absorption - from MadScientst Network
Best Student Experiment
Heat Absorption and Emissivity - Information from others
JP: As you probably already know, dark colors (black) will heat up more than light colors (white). Try using thermometer strips sold at pet stores (to stick on the insides of reptile cages to monitor temperature). They're cheap, don't break, are flat so you can put them under a piece of paper (if that's what material you're using) to check your temperatures. Try some materials with different reflective surfaces too (foil; shiny black vs. rough-surfaced black for example).
Chris Willard: I would follow Ben Franklin's observations, put different colors on a block of ice (he used snow). Set the ice in the sun and observe how the darker colors melt down into the ice faster (presuming it will, I've not tried this). another idea might be to set a thermometer under pieces of cloth that are set in the sun or under a lamp to measure different temperatures.
Anonymous: White reflects more energy than black does. Absorbed energy is of course not destroyed but usually converted to heat so the answer to your question is yes, makes a difference.
Mac: Color can affect heat absorption because of emissivity. A number of variables can enter into the picture, so if you conducted an experiment, you'd need to proceed carefully, to avoid skewed results. Emissivity would probably be the key differentiator in your question. (Look up emissivity in the dictionary).
Given two identical glass containers - one being of one color A and another being of another color B and that they would be filled with, say, some identical heated liquid, and then allowed to cool -
And given that the emissivity of container colored A and the emissivity of container colored B is substantially different, then the rates of cooling would be different. [You would need to measure or otherwise determine what the 'emissivity' of each specifically colored glass is.]
Emissivity of materials is of significant concern in some industries - for instance - if you are building a spaceship - and you want to keep parts of the spaceship cool or other parts warmer. The 'color' (more precisely, the emissivity) of the surface of the ship will determine whether that portion of the spaceship will be cold, cool, warm, or hot.
There are lists that give the values of emissivity of various materials - in books on spacecraft design, thermal properties handbooks, and similar texts.
Two of the main attributes you would want to look at in an experiment that would demonstrate this would be 1. the material's emissivity and 2. the material's thermal conductivity.
To remove multiple external variables from your experiment - you might want to place both of the glasses of liquid into a black box (keeping them out of sunlight/away from external heat / light sources). Don't put them in the microwave either! :-)
And if do perform an experiment - if you use two thermometers or thermocouples, be sure they are calibrated. And gosh - publish your findings here if you do perform the experiment.
If you paint one glass Black and the other glass White, which container do you think will cool faster? Any hunch?
Anonymous: About the absorption of heat and emissivity in coffee cups: The cups would take heat energy from the coffee at same rate, given same material of cup, as this is conductive heat transfer, while the white cup will radiate heat to surrounding air more slowly than the black cup, and so in total the black cup of coffee will cool down quicker.
An excellent student experiment about color and heat absorption
The following is documentation of a student's experiment with color and heat absorption. We only know her as "Madeline" and here's the research that she posted on the bulletin board at Color Matters, January, 2000.
Question
Does the amount of thermal energy (heat) produced by a colored fabric after 30 minutes of intense light relate to its position in the spectrum?
Hypothesis
When a color (colored fabric) absorbs light, it turns the light into thermal energy (heat). The more light a color absorbs, the more thermal energy it produces. Black fabric absorbs all colors of light and is therefore warmer than white fabric which reflects all colors. I predict that the colors of the spectrum appearing the darkest and most like black (violet, indigo, and forest green) will produce the most thermal energy. The other colors (red, orange, and yellow), will produce the least thermal energy because they appear lighter or more like white.
Materials
1. a thermometer (preferably an indoor/outdoor thermometer because they have the largest temperature range)
2. a 1’ x 1’ piece of heavy corrugated cardboard
3. tape
4. a clock, stopwatch, or timer
5. sunlight (If you’re short on sunlight, use a with a halogen floodlight, at least 100 watts. A halogen bulb is a good choice because it has a high light intensity and its light spectrum is very similar to sunlight.)
6. six 100% cotton T-shirts (or pieces of cloth) in red, orange, yellow, forest green, indigo, and violet
Procedure
A simple way to measure how much thermal energy a colored material produces is to measure the changes in its temperature:
1. Tape the thermometer in the center of the cardboard. Make sure the tape doesn’t cover the thermometer bulb.
2. Set the cardboard/thermometer indoors, out of direct sunlight.
3. Lay the red cloth over the cardboard/thermometer so it is touching the thermometer bulb.
4. Set the lamp so the bulb is 2 feet away from and perpendicular to the cardboard/cloth.
Turn the lamp on.
5. Position the cardboard/cloth so the thermometer bulb is in the center of the beam of light.
6. Wait 30 minutes, then record the temperature under the cloth.
7. Turn the light off and take the cloth off the cardboard.
8. Repeat steps 3 through 8 using each of the other colors of cloths. (Orange, yellow, forest green, indigo, violet.)
9. Repeat the experiment at least 6 times and calculate the average temperatures for each color.
Conclusion
My hypothesis is correct. The darker colors (forest green, indigo, violet) produced the most thermal energy after 30 minutes of intense light. The lighter colors (red, orange, yellow) produced smaller amounts of thermal energy. (The average recorded temperature (°F) for each of the colors is shown in Graph 1.) Interestingly, the temperatures of the fabrics fell in to two groups instead of increasing as the colors got closer to violet. The difference between the temperatures of the red, orange, and yellow fabric was minimal, only 10ths of a degree. The same thing was true for violet, indigo, and forest green fabric. However, the difference between the temperatures of the two groups was a little more than 3 degrees (Fahrenheit). In conclusion, even though violet, indigo, and forest green are generally referred to as "cool" colors, you will be warmer if you wear them! You may not be any warmer if you wear blue instead of green, or green instead of purple. Similarly, it won’t make a difference if you wear red instead of yellow, or yellow instead of orange, but on a hot day, wear one of the warm colors!
Bibliography
Gardner, Robert. Science Projects About Light. Springfield, New Jersey: Enslow Publishers, Inc., 1994, p. 92
Morton, J.L. Color Matters - ElecroMagnetic Color - 1995-1999
About Light
There are many different kinds of light. The different kinds have different wavelengths. Ultraviolet light, for example, has a wavelength of 10-8 meters. Visible colors have a wavelength of about 10-6 meters, the diameter of a bacteria. Infrared light also has a wavelength of about 10-6 meters, but has a longer wavelength than the visible colors. The different colors of visible light have different wavelengths, but the wavelengths are very similar. Violet light has the shortest wavelength, is the coolest, and is closest to ultraviolet light. Red light has the longest wavelength, is the warmest, and is closest to infrared light. The other colors of visible light increase in wavelength and warmth as they get closer to red and infrared light. (For example, yellow light has a longer wavelength and is warmer than indigo light.)
When you shine white light (the light that includes all the visible colors) on a colored object, the object will appear to be the color of the light it reflects. All the other visible colors are absorbed. If the object reflects a warm color (red, orange, yellow) it will be cooler than an object which absorbs them. For example, if you shine light on a blue object, it will absorb the warm red light, and will be warmer than a red object which would reflect that light.
Results of Experiment (completed 8 times)
Cloth Color Red Orange Yellow Dk. Green Indigo Violet
Temperature( F) 76 77 76 80 81 78
78 76 77 76 82 78
76 77 78 83 79 82
76 79 77 80 81 84
78 78 76 86 83 82
78 75 78 81 82 80
78 78 79 79 78 84
77 77 77 81 81 80 Standard Deviation 0.991031 1.246423 1.035098 2.915476 1.642081 2.390457
Average Temp. ( F) 77.13 77.13 77.25 80.75 80.88 81
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Links to More Science Projects
Here's a compilation of all the pages with information from students who are conducting scientific color experiments.
Does Color Affect Taste?
Color and Water Evaporation
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