Quest Chapter 28. Remember: We see by color addition. How do we get white with color addition? So, is it a color?

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1 1 Why do we not list black and white as colors? 1. People usually think black and white should only reflect dark and light in a image. They cannot represent the colorful world. 2. Black should not be regarded as a color; an early mistake in theory caused white to be regarded as a color. 3. We have a subjective mind. 4. Black means low intensity; white is the result of an additive mixture of all the colors. 2 Interestingly, a steam radiator warms a room more by convection than by radiation. Nevertheless, with respect to its radiating properties, what is the most efficient color for a steam radiator? 1. red 2. blue 3. black 4. white 3 Why do people wear light-colored clothing in summer and dark-colored clothing in winter? I) Dark clothing absorbs more light so it can keep you warmer; II) The absorbed light is converted to kinetic energy of the atoms in the clothing; III) Dark clothing is usually thicker; IV) Light clothing is lighter. 1. None of these 2. I only 3. All of these 4. IV only 5. I and II only 6. II and IV only 7. III only 8. II only 9. I and III only 10. III and IV only Quest Chapter 28 Remember: We see by color How do we get white with color addition? So, is it a color? What is black? Can we get black with color addition? Objects radiate heat based on their specific heat and temperature. The effect NOT based on their color. Objects absorb radiant heat differently based on their color. Answer the question based on heat absorbtion. Think about the absorption of light. What happens to the energy? It can be reflected, transmitted, or absorbed. Reflected means it bounces off the material and is then gone. Transmitted means it goes through the material. Absorbed means the energy goes into the material and increases its internal energy. Which if the roman numerals is correct? Choose them first, then choose the answer that matches.

2 4 The leaves of a tree are bright green. What does a leaf s absorption spectrum look like? 1. The leaf would reflect sunlight. 2. The leaf would absorb all colors except green. 3. None of these 4. The leaf would reflect all colors except green. 5. The leaf would absorb sunlight. 5 In a dress shop with only fluorescent lighting, a customer insists on taking dresses into the daylight at the doorway to check their color. Is she being reasonable? 1. Yes; in sunlight she can see much more clearly. 2. No; if all customers make this kind of request, the shop will lose control. 3. Yes; under fluorescent lighting, blue colors will be accented. Colors appear quite different in sunlight. 4. No; the light in the dress shop is enough for her to see the effect. 6 The yellow-green light emitted by street lights matches the yellow-green color to which the human eye is most sensitive. Consequently, a 100-watt street light emits light that is better seen at night. Similarly, the monitored sound intensities of television commercials are louder than the sound from regular programming, yet don t exceed the regulated intensities. At what frequencies do advertisers concentrate the commercial s sound? 1. The sound of commercials is concentrated at the high-frequency region of audible sound frequencies. 2. The sound of commercials is concentrated at the frequency of 60 Hz. 3. The sound of commercials is concentrated at the low-frequency region of audible sound frequencies. 4. The sound of commercials is concentrated at frequencies to which the ear is most sensitive. Absorption: Think color subtraction. If you see green, what is being absorbed? What is different about fluorescent lights than sunlight? Read carefully. Read all the answers before selecting one.

3 7 What is the relationship between the frequency of light and its color? 1. Lights of different frequencies are perceived as different colors. 2. None of these 3. The highest-frequency light we detect appears to most people as the color red. 4. There is no relationship between the frequency of light and its color. 5. The lowest-frequency light we detect appears to most people as the color violet. 8 Fire engines used to be red. Now many of them are yellow-green. Why was the color changed? 1. People got tired of the red color and a color change was advised. 2. Red color makes people feel nervous. 3. Red color is not easy to notice among fires. 4. They are most likely to be noticed if they are yellow-green; the eye is most sensitive to that color. 9 The radiation curve of the sun shows that the brightest light from the sun is yellow-green. Why then do we see the sun as whitish instead of yellow-green? 1. When sunlight passes through the air, yellow-green components are absorbed by the air. 2. The yellow-green light has very strong intensity, so when it arrives at our eyes, we can only feel it as strong white light. 3. All colors mix to produce the white light we see. 4. Outside the Earth you will see yellowgreen light of the sun. Read carefully. Cross out wrong statements. What are the differences in the properties of red versus yellowgreen frequencies of light in terms of how our eyes work? How do we make white? What is another way to say colors are added?

4 10 An object that looks white when exposed to sunlight reflects all colors of light. What does a white object look like when it is exposed to red light? 1. A white object will look red when exposed to red light. 2. A white object will look yellow when exposed to red light. 3. A white object will look the same when exposed to red light. 11 What does a red object look like when it is exposed to blue light? 1. A red object will appear dark when exposed to blue light 2. A red object will appear bright when exposed to blue light 12 A spotlight is coated so that it won t transmit yellow light from its white-hot filament. What color is the emerging beam of light? 1. black 2. red 3. yellow 4. green 5. blue 13 If sunlight were somehow green instead of white, what color garment would be most advisable on an uncomfortable hot day? On a very cold day? 1. Green for a hot day and white for a 2. Blue for a hot day and green for a 3. Red for a hot day and yellow for a 4. Green for a hot day and magenta for a 5. Yellow for a hot day and blue for a It looks white because it reflects ALL the colors of sunlight. Shining a single color will reflect what color or colors? What color does the object reflect when exposed to white light? How much of that color is shining on it? What is the complement to yellow? How much energy do you want to absorb on a hot day? What color would reflect the most energy?

5 14 If the atmosphere did not scatter light, what would you see when you looked at the daytime sky? I) The sky would be dark; II) Sunlight would pass right through atmosphere; III) Light would be scattered to your eyes. 1. I and III only 2. All of these 3. None of these 4. I and II only 5. II and III only 15 Why does the sky appear darker blue when you are at high altitudes? 1. There is less air above you and consequently less scattering of sunlight. 2. There is less sunshine at high altitudes than at lower altitudes. 3. There are more red-absorbing molecules in the air at high altitudes. 4. There is less air above you and consequently more scattering of sunlight. 16 What color is obtained when you mix yellow light and blue light? 1. blue 2. red 3. green 4. magenta 5. white 6. yellow 7. cyan 17 What color should be combined with green light to produce white light? 1. yellow 2. white 3. magenta 4. red 5. green 6. cyan 7. blue Scattering causes the sky to be what color now? What would happen the properties were different and the light was not scattered? Select the roman numerals that are correct and then pick the correct answer. Think of where you are when you see the light blue color of the sky and what causes the sky to be light blue. What happens to your position when you go to a higher altitude? Where are you in that process? Think of the primary and complementary colors in color Think of the primary and complementary colors in color

6 18 What color is the mixture of magenta, yellow and cyan light? 1. green 2. red 3. white 4. magenta 5. blue 6. yellow 19 If the sky on a certain planet in the solar system were normally orange, what color would sunset be? 1. yellow 2. white 3. blue 4. black 5. orange 6. red 20 Why does the sun look red at sunrise and sunset but not at noon? 1. Red light is easily scattered through the air since its frequency is the lowest. At noon, sunlight travels through the least amount of atmosphere with little transmission of high frequency light to the surface. 2. The sun is colder at sunrise and sunset than at noon. 3. Red light is easily transmitted through the air since its frequency is the lowest. At noon, sunlight travels through the least amount of atmosphere with little scattering of high frequency light to the surface. 4. The temperature at noon is warmer than at sunrise and sunset. 5. Our eyes are more sensitive to the red light at sunrise and sunset than at noon. 6. The sun itself is red at sunrise and sunset, but is yellow at noon; it has nothing to do with the effect of the atmosphere. Think of the primary and complementary colors in color Think of the scattering effect. What would be left to see at sunset? Think of the whole blue sky problem. Why is it scattered first? What is different about sunset/sunrise that would make red scatter at those times?

7 21 Does the KE of a car change more when it accelerates from 27 km/h to 37 km/h or when it accelerates from 37 km/h to 47 km/h? 1. No difference 2. From 27 km/h to 37 km/h 3. More information is needed. 4. From 37 km/h to 47 km/h 22 Two objects of same material are travelling near you. Object A is a 1.3 kg mass traveling 8.6 m/s; object B is a 2 kg mass traveling 5 m/s. Which object would make you feel worse if you are hit by it? 1. B 2. Unable to determine 3. the same 4. A Remember: KE = ½ mv 2 Does the mass change? Find the KE for the three velocities and compare the changes. What could you check? If the objects had the same mass, the answer would be obvious. Likewise, if they had different masses but the same velocity, the answer would be obvious. What to do What to do Try examining the KE of each object. Since the problem doesn t state you are moving after the collision, you have to handle all of that energy.