To Wear or Not to Wear: Do Colors Affect how Warm a Person Becomes?

Transcription

1 To Wear or Not to Wear: Do Colors Affect how Warm a Person Becomes? Submitted by :P12 Date: 9 May 2018 Science Division: Physical

2 1 Table of Contents Topic Page Research 1-4 Purpose.. 5 Hypothesis. 5 Materials. 5 Procedure Results and Analysis Conclusion Work Cited 13 Acknowledgements 14

3 2 To Wear or Not to Wear: Do Colors Affect How Warm a Person Becomes? Research: Visible light is the part of the electromagnetic spectrum that is visible to the eye. It consists of electromagnetic waves with wavelengths between 400 nm and 700 nm. Wavelength is an important characteristic of light, especially when talking about colors, because the wavelength determines the color. When visible light, also called white light, passes through a prism it is broken into seven major colors of light. These colors are red, orange, yellow, green, blue, indigo, and violet. Each color has its own unique frequency as well as wavelength (Rogers et al., 216). The primary colors of light are red, green, and blue. To create secondary colors of light, the process of additive mixing is used. This is when different combinations of red, green, and blue light are mixed together to form the secondary colors, cyan, magenta, and yellow. Mixing other combinations of red, blue and green create all of the other colors of light. Complimentary colors are formed when any two colors are mixed together and form white light (Rogers, et al., 216). The color that an object appears is the color of light that it is reflecting. A material absorbs all colors except the color that it appears; this color is reflected by the material. Each colored object contains pigments. The three primary colors of pigments are yellow, magenta, and cyan. These colors can be mixed together to form any visible color (Biggs, et al., 668). Pigments absorb certain wavelengths of colors so an orange shirt would absorb all light except orange light. It would reflect orange light. White reflects all light, and black absorbs all light. White and black are achromatic colors, which means without color (Rogers et al., 217).

4 3 The definition of heat is a form of energy that flows from one place to another because of a difference in temperature. (Rogers, et al. 110). Temperature is a measure of how fast the molecules in an object are moving. The faster the particles are moving, the hotter the object is. When a substance absorbs light, its internal energy is increased (Rogers, et al. 110). The first law of thermodynamics states that energy cannot be lost or gained: it is only changed from one form to the other. When light hits an object, the energy has to go somewhere, so it is changed into heat energy. The energy causes the molecules to move faster resulting in an increase in temperature (Color vs. Heat). The more light that is absorbed by an object, the more light energy that is transformed into heat energy. There are three types of heat transfer; convection, conduction, and radiation. In convection, heat is transferred in gases and liquids. When a gas or a liquid is heated, the part closest to the heat source will expand. This causes the material to become less dense, therefore causing it to rise. The denser and cooler liquid or gas at the top would then sink. This rising and sinking motion causes convection currents (Rogers, et al., 112). In conduction, heat is transferred in solids. Conduction works because the energy of the particles closest to the heat source increase, causing them to vibrate. This causes the particles to pass their energy to other particles by bumping into them. Heat energy is spread throughout the solid by a chain reaction of particles bumping into each other (Rogers, et al., 113). In radiation, energy moves in the form of electromagnetic waves. The Sun sends out infrared radiation, which is absorbed by darker colors causing them to gain heat and reflected by lighter colors allowing them to stay cooler (Rogers, et al., 113). Radiation occurs because the Sun s temperature is

5 4 higher than the Earth s temperature. If two objects with different temperatures are put next to each other, the heat will flow from the hotter object to the cooler object in order to reach equilibrium (Giancoli, 241).

6 5 Purpose: Do different colors of clothing absorb heat differently? Hypothesis: If darker colors absorb more light than lighter colored fabrics, then the darker colored fabrics will become the warmest and the lighter colored fabrics will be cooler. Red, orange and yellow fabric will absorb the least amount of heat because they are lighter colors and therefore reflect more light. Green, blue and violet cloth will gain more heat because they are darker colors and therefore absorb more light. The black fabric will become the hottest because it absorbs all visible light waves and the white fabric will be the coolest because it reflects all visible light waves. Materials: Cotton fabric (1 meter each) in black, white, red, orange, yellow, green, blue and violet 100 watt halogen floodlight bulb and lamp Wireless remote thermometer 30 cm x 30 cm piece of cardboard Tape String to suspend lamp over fabric Stopwatch, clock or timer

7 6 Procedure: Independent variable: Color of fabric Dependent variable: temperature under fabric Constants: same size fabric, same type of fabric, same thickness of fabric, same length of light exposure, same type of light and light holder, same distance of fabric from light, same distance of thermometer from light and fabric, same thermometer, same environment Control: no fabric 1. Insert halogen bulb into lamp. 2. Choose a flat area to use while testing fabrics. 3. Tape thermometer probe or sensor to piece of cardboard (be sure not to tape over the probe tip or sensor). 4. Place cardboard on the flat surface. 5. Tie a string on the lamp handle and suspend bulb 45 cm directly above the thermometer probe or sensor. 6. Fold white piece of fabric until it is eight (8) layers thick. 7. Lay fabric over the thermometer. 8. Record the starting temperature. 9. Turn on the lamp and measure and record the temperature after five (5) and ten (10) minutes. 10. Turn off the lamp.

8 7 11. Calculate the temperature gained after five (5) and ten (10) minutes by subtracting the initial temperature from the five (5) and ten (10) minute temperature readings. 12. Allow thermometer to cool to room temperature. 13. Repeat steps six (6) through twelve (12) two (2) more times. 14. Remove fabric. 15. Repeat steps six (6) through fourteen (14) with black, red, orange, yellow, green, blue, and violet fabrics. 16. Repeat steps eight (8) through eleven (11) without any fabric over the thermometer as the control.

9 8 Results and Analysis: Fabric Color and Temperature Gained Temperature ( C) Average Fabric Color Temperature Gained ( C) After Before 5 minutes 10 minutes 5 min 10 min Red Trial Trial Trial Orange-Trial Trial Trial Yellow - Trial Trial Trial White- Trial Trial Trial Green - Trial Trial Trial Blue-- Trial Trial Trial Violet- Trial Trial Trial Black- Trial Trial Trial Control-Trial Trial Trial Avg.Temp. Gained = (Temp. after Trial 1 before temp) + (Temp. after Trial 2 before temp) + (Temp. after Trial 3 before temp) 3

10 9 Average Temp. Gained (Celsius) Temperature Gained vs. Fabric Color Fabric Color Legend Temp after 5 min (solid bar without border) Temp. after 10 min (solid bar with blue border) The red, orange, yellow and white fabric heated up less than the green, blue, violet and black fabric. The black fabric absorbed the most heat.

11 10 Conclusion: The results partially support the hypothesis in that the temperature under the lighter colors (red, orange and yellow) was cooler than under the darker colors (blue, green and violet) and the temperature under the black fabric was the highest. The hypothesis was incorrect for the white fabric, the temperature under the white fabric was not the lowest temperature, it was the same temperature as the red, orange and yellow fabrics. The average temperature gained for the lighter colors after five minutes was about five degrees Celsius, and after ten minutes, it was between six and seven degrees Celsius. The average temperature gained for the darker colors was about eight to ten degrees Celsius, and after ten minutes it was about ten to thirteen degrees Celsius. The lighter colors did not gain as much heat because they reflected most of the longer wavelength light rays. There was almost no difference between the temperature gain in red, orange and yellow fabrics so the minor differences in the wavelengths of light being reflected by these colors did not affect the temperature. The darker colors gained more heat because they absorbed most of the longer light rays and reflected the shorter wavelength rays. Again, there was very little difference between green, violet and blue fabrics so the minor differences in the wavelengths of the light absorbed did not affect the temperature. Black, which absorbs all light showed the highest increase in temperature. Infrared light, which is heat energy, is a longer wavelength similar to the red, orange and yellow wavelengths. The red, yellow and orange fabric reflected the longer wavelengths so that may be why those fabrics absorbed less heat. The blue, violet and green fabrics reflected the shorter wavelengths but absorbed the longer wavelengths so that may be the reason they became warmer.

12 11 Two different temperatures were tested for each trial. Five and ten minutes were chosen because they provided accurate temperatures. After five minutes, the temperature was towards the middle of the total temperature gained. After ten minutes, the temperature had pretty much reached the highest temperature the fabric would gain. Longer times were tested while the procedure was being developed that indicated there was no further temperature gain beyond ten minutes. The temperature increased mainly because light energy was converted into heat energy. Visible light waves carry energy. When a light ray hits an object, the energy has to go somewhere according to the first law of thermodynamics. The more light that is absorbed, and the longer the wavelength absorbed, the more heat that is generated. As a result, the darker colors that absorbed more of the longer wavelengths of light became warmer. In an experiment such as this, there isn t pure visible light. There might be infrared or possibly UV rays depending on the light source. A halogen lamp was used because it reduces the amount of infrared and UV rays and emits mostly visible light rays. As a control, the temperature gain for the thermometer alone (no fabric covering it) was determined by placing the thermometer under the lamp at the same distance as for the samples and reading it after five and ten minutes. According to the results, a lighter colored shirt would reflect more light and keep a person cooler, while a darker colored shirt would absorb more light and cause a person to become warmer. It follows that red, orange, yellow and white shirts would be best for summer and green, blue, black and violet shirts would be better for winter. An improvement on the lab procedure would be to replace the halogen lamp with the Sun

13 12 so the results are more relevant to wearing clothes outside. It would also be interesting to compare the temperature increase for different fabric types.

14 13 Work Cited Biggs, Alton, et al. Glencoe Science: Level Green. New York: Glencoe/McGraw-Hill, Print. Color vs. Heat. Web. 5 May < Giancoli, Douglas C. Physics. Engelwood Cliffs: Prentice-Hall, Inc., Print. Residential Energy Bookshelf. Web. 7 May < Rogers, Kersteen, et al. The Usborne Internet-Linked Science Encyclopedia. Saffron Hill, London: Usborne Publishing Ltd., Print.

15 14 Acknowledgements I would like to thank my mom and dad for helping me with the experimentation and for putting up with my constant procrastination. I wouldn t have been able to carry out my experiment if they hadn t spent their time (and money) on my experiment and supplies.