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TO GO TO ANY OF THE PAGES LISTED BELOW, CLICK ON ITS TITLE CHAPTER 19 Light 19-1 19-2 19-3 19-4 19-5 19-6 19-7 19-8 19-9 19-10 1 What is the electromagnetic spectrum? Lesson Review 2 What is light? Lesson Review 3 Light-Years Enrichment Activity for Lesson 19-2 4 How do light waves travel? Lesson Review 5 Speed of Light in Different Materials Enrichment Activity for Lesson 19-3 6 What are sources of light? Lesson Review 7 Objects and Light Enrichment Activity for Lesson 19-4 8 What is photosynthesis? Lesson Review 9 How do lenses refract light? Lesson Review 10 How do you see? Lesson Review 11 How do mirrors reflect light? Lesson Review 12 Telescopes Enrichment Activity for Lesson 19-8 13 What is color? Lesson Review 14 How can light be used? Lesson Review 15 BIG IDEA Integrating Technology: How is light used in the home? Lesson Review 16 THE Chapter 19 Key Term Review 17 Chapter 19 Test 18 Chapter 19 Answer Key 20 Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 1 Name Class Date 19-1 What is the electromagnetic spectrum? Lesson Review Match each description in Column A with the correct term in Column B. Write the letters of the correct answers in the spaces provided. Column B Column A __________ 1. usually given off during nuclear reactions a. microwaves __________ 2. sometimes used to kill bacteria b. gamma rays __________ 3. the only part of the electromagnetic spectrum that the human eye can see c. __________ 4. can be used to form images of bones and internal organs __________ 5. felt as heat __________ 6. waves with the longest wavelength and lowest frequency __________ 7. range of electromagnetic waves __________ 8. often used for wireless communications and microwave ovens X-rays d. ultraviolet rays e. radio waves f. the visible spectrum g. infrared rays h. electromagnetic spectrum Skill Challenge Skills: interpreting diagrams, inferring The diagram below shows a model of the electromagnetic spectrum. Use the diagram to answer the questions. 1. Name three types of electromagnetic waves that have wavelengths longer than that of visible light. ___________________________________________________________________________________________ 2. Which type of wave has the shortest wavelength? ______________________________________________ 3. Which color in the visible spectrum has the shortest wavelength? ________________________________ 4. Which color in the visible spectrum has the longest wavelength? _________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 2 Name Class Date 19-2 What is light? Lesson Review Complete the following. 1. Light is a form of ____________________________________________________________________ energy. 2. Light is made up of photons, which are ______________________________________________________ . 3. A _____________________________________________ of light is made up of a stream of many photons. 4. Each photon carries a certain amount of ______________________________________________ , although some photons have more _________________________________________________________ than others. 5. Light travels in ________________________________________________________________________ lines. 6. A ___________________________________ of light shows the direction of a light beam; it will continue to travel in a ___________________________________________________ unless its direction is changed. Skill Challenge Skills: analyzing, organizing Light can be changed into other forms of energy. Analyze the examples below and decide what form or forms of energy light is being changed into. Place a check mark in the correct columns. LIGHT AND ENERGY CHANGES Example Forms of Energy Heat Electrical Mechanical Chemical 1. A calculator is powered by a solar cell. 2. Plants make food with sunlight, water, and CO2. 3. A blacktop surface gets warmer when sunlight strikes it. 4. A scientist invents a solar-powered car. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 3 Name Class Date Light-Years Enrichment Activity for Lesson 19-2 Skills: interpreting tables, calculating Read the passage. Then, study the table below that shows the distance in lightyears from Earth to several stars. Refer to the table as you answer the questions that follow. Round your answers to the nearest tenth. A light-year sounds like a measurement of time, but it is actually a measurement of distance. A light-year is the distance that light travels in one year. That may sound like a very long way, and it is. Light travels at a speed of approximately 300,000 km/s. That means that in one year, light travels approximately 9.5 trillion km. The light from an object 1 light-year away takes 1 year to reach you. If a person living on a planet 1 light-year away turned on a light, it would take 1 year for the light to reach Earth. The stars in the universe are so far from Earth that their light takes many years to reach Earth. Have you ever thought that when you look at a star, you are seeing light that is many years old? DISTANCE FROM STARS TO EARTH Star Approximate Distance (Light-years) Proxima Centauri 4.3 Sirius 8.6 Vega 26.5 Betelguese 520.0 Polaris 680.0 Rigel 900.0 1. How far in kilometers is Sirius from Earth? ____________________________________________________ 2. Sirius is twice as far from Earth as which star? _________________________________________________ 3. How far in kilometers is Rigel from Earth? ____________________________________________________ 4. From which star—Polaris or Vega—does light take longer to reach Earth? ________________________ 5. Suppose that you look at the star Rigel. How long ago did its light start traveling toward you? ___________________________________________________________________________________________ 6. Would it be possible for you to see the star Betelgeuse, even if that star had died hundreds of years ago? Explain your answer. ___________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 4 Name Class Date 19-3 How do light waves travel? Lesson Review Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. ____________________ 1. In a transverse wave, the particles of the medium move up and down at right angles to the direction of wave motion. ____________________ 2. A light wave is a longitudinal wave. ____________________ 3. Light waves need a medium in which to travel. ____________________ 4. A sound wave is a longitudinal wave. ____________________ 5. Sound waves need a medium in which to travel. ____________________ 6. Light waves travel fastest in air. ____________________ 7. The amplitude of light is the distance from the crest or trough of one wave to the crest or trough of the next wave. ____________________ 8. The frequency of light is about 300,000 km/sec. ____________________ 9. The wavelength is the height of the wave. ____________________ 10. All electromagnetic waves travel at the same speed. Skill Challenge Skills: interpreting diagrams, identifying, analyzing The diagram below shows a wave. Refer to the diagram as you answer the questions below. 1. What property of the wave is shown by the section labeled C? ___________________________________ 2. What property of the wave is shown by the portion of the wave labeled D? _______________________ 3. In what direction is the wave traveling? _______________________________________________________ 4. In this wave, which way are the particles moving? _____________________________________________ 5. Is this wave a transverse wave or a longitudinal wave? How can you tell? ________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 5 Name Class Date Speed of Light in Different Materials Enrichment Activity for Lesson 19-3 Skills: interpreting tables, analyzing Light travels at different speeds in different materials. Study the table. Then, answer the questions. DISTANCE OF LIGHT IN DIFFERENT MATERIALS Material Speed of Light (km/s) Vacuum 300,000 Air 299,000 Ice 229,000 Water 225,000 Glass 197,000 Diamond 124,000 1. In which material listed does light travel slowest? ______________________________________________ 2. In which material does light travel fastest? ____________________________________________________ 3. How does the speed of light traveling from outer space change as it approaches Earth? ____________ ___________________________________________________________________________________________ 4. Do you think the speed of light may be related to the density of a material? If so, in what way? Explain your answer. _______________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 5. Study the diagram below. Then, explain when you would expect the light to speed up or slow down as it follows a path through the glass of ice water. ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 6 Name Class Date 19-4 What are sources of light? Lesson Review Match each term in Column B with its description in Column A. Write the letter in the space provided. Column B Column A __________ 1. material that transmits light easily a. translucent __________ 2. material that blocks light b. shadow __________ 3. object that gives off its own light c. transparent __________ 4. object that reflects light d. opaque __________ 5. material that transmits some light e. luminous __________ 6. formed when a material blocks light f. illuminated Skill Challenge Skills: observing, classifying, organizing Decide whether each material or object listed below is illuminated, luminous, opaque, translucent, or transparent. Place a check mark in the correct column. Material/Object Illuminated Luminous Opaque Translucent Transparent 1. Plastic food wrap 2. Lighted candle 3. Stained glass 4. Tracing paper 5. Piece of wood 6. Moon 7. Cardboard 8. Sheer fabric 9. Spotlight 10. Orange juice Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 7 Name Class Date Objects and Light Enrichment Activity for Lesson 19-4 Skills: analyzing, classifying Study each of the drawings below. Decide whether the object shown is illuminated, luminous, opaque, translucent, or transparent. Write your answer in the space below each picture. 1. ________________________________________ 2. ________________________________________ 3. ________________________________________ 4. ________________________________________ 5. ________________________________________ 6. ________________________________________ 7. ________________________________________ 8. ________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 8 Name Class Date 19-5 What is photosynthesis? Lesson Review Complete the following. 1. In photosynthesis, plants use energy from the Sun to make _____________________________________ . 2. In photosynthesis, light energy is converted into ________________________________________ energy. 3. Sunlight is absorbed mostly by the _________________________________________________ of a plant. 4. The substance in a leaf that absorbs sunlight is called __________________________________________ . 5. This substance absorbs all colors of light except ___________________________________________ light. 6. As the Sun moves across the sky, the leaves of a plant will _____________________________________ . 7. Light energy can be converted to heat energy, __________________________ energy, chemical energy, or other forms of energy. 8. Plant leaves look green because _____________________________________________________________ . Skill Challenge Skills: interpreting diagrams, relating, analyzing The diagram and equation below show the process of photosynthesis in plants. Study the diagram and equation. Then, answer the questions. 1. According to the equation, what is needed in order for photosynthesis to take place? _______________________________________ 2. What products are produced by photosynthesis? ________________________ _______________________________________ 3. How does water enter a plant? How does it reach the leaf? ________________________ _______________________________________ 4. What is a plant’s source of carbon dioxide? How does carbon dioxide enter the leaf? _______________________________________ 5. How does sunlight enter the leaf of a plant? ___________________________________________________ ___________________________________________________________________________________________ 6. How is oxygen released by the leaf? __________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 9 Name Class Date 19-6 How do lenses refract light? Lesson Review Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. Write your answers in the spaces provided. ____________________ 1. A lens that curves outward is called a concave lens. ____________________ 2. A lens is a transparent material that reflects light. ____________________ 3. Light is bent when it passes from one medium into another at an angle other than 90°. ____________________ 4. Light that passes through a convex lens is bent outward. ____________________ 5. The point at which light rays are brought together after passing through a convex lens is called the focal point. ____________________ 6. After light rays pass through a convex lens, they are bent away from the lens. ____________________ 7. The focal length is the distance between the image and the focal point. ____________________ 8. A real image can be projected onto a screen. Skill Challenge Skills: diagramming, identifying On each diagram below, use colored pencils to draw the path of the light rays as they pass through the lens. Identify each lens as a concave lens or a convex lens. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 10 Name Class Date 19-7 How do you see? Lesson Review Answer the following questions. 1. What is the cornea? What is its purpose? ______________________________________________________ ___________________________________________________________________________________________ 2. What is the pupil? __________________________________________________________________________ 3. What is the iris? How does it work? __________________________________________________________ ___________________________________________________________________________________________ 4. What is the relationship between the lens and the retina? _______________________________________ ___________________________________________________________________________________________ 5. What is an image? __________________________________________________________________________ 6. What does the retina do? ____________________________________________________________________ 7. What is the purpose of the optic nerve? _______________________________________________________ ___________________________________________________________________________________________ 8. Where is the upside-down image produced by the lens converted to a right-side-up image? ___________________________________________________________________________________________ Skill Challenge Skills: identifying, interpreting a diagram Identify the parts of the eye shown on the diagram below. Use the following terms: cornea, iris, pupil, lens, retina, and optic nerve. 1. ________________________________ 2. ________________________________ 3. ________________________________ 4. ________________________________ 5. ________________________________ 6. ________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 11 Name Class Date 19-8 How do mirrors reflect light? Lesson Review Decide whether each description refers to regular reflection or diffuse reflection. Write R for regular reflection or D for diffuse reflection in the spaces provided. __________ 1. forms an irregular image _________ 5. equal values for angle of incidence and angle of reflection _________ 6. occurs when a surface is rough _________ 7. formed by smooth mirrors _________ 8. different angles of reflection when light strikes a surface __________ 2. forms a clear image __________ 3. can produce a distorted image __________ 4. occurs only when a surface is smooth and even Skill Challenge Skills: interpreting diagrams, inferring Study the diagram below. Then, answer the questions. 1. In Figure 1, which lines represent the original light rays? Which lines represent reflected rays? __________________________________________________________________________________________ 2. Which set of lines is parallel in Figure 1? _____________________________________________________ 3. What are the angles labeled a and b? _________________________________________________________ 4. If angle a = 30°, what is the size of angle b? ___________________________________________________ 5. If angle a = 30°, what is the size of the other angles formed by the other incident rays? By the other reflected rays? ____________________________________________________________________________ 6. In Figure 2, which lines represent incident rays? Which represent reflected rays? _________________ 7. Is either set of lines parallel? If so, which set or sets? ___________________________________________ 8. What type of reflection is shown in Figure 1? In Figure 2? ______________________________________ 9. According to the diagrams, what happens to the original parallel rays in each kind of reflection? __________________________________________________________________________________________ __________________________________________________________________________________________ 10. What conclusion can you draw about the angles at which light is reflected in each kind of reflection? ________________________________________________________________________________ __________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 12 Name Class Date Telescopes Enrichment Activity for Lesson 19-8 Skills: analyzing, inferring, comparing The following passage describes two types of telescopes. Read the passage. Then, answer the questions. Light telescopes are instruments used to make distant objects appear closer. There are two kinds of light telescopes: refracting telescopes and reflecting telescopes. A refracting telescope has two convex lenses. The lenses are called the objective lens and the eyepiece lens. The objective lens focuses the light entering it. The objective lens is located at one end of a tube. This lens forms a real, upside-down image. The eyepiece lens is located at the opposite end of the tube. This is the lens you look through. The eyepiece lens acts like a magnifying glass. It makes the real image formed by the objective lens larger. The eyepiece lens forms an enlarged, virtual image. A reflecting telescope does not have an objective lens. This kind of telescope uses a concave mirror instead of a lens to focus light. The mirror is located at one end of a tube. Light enters the tube at the other end, travels the length of the tube, and strikes the concave mirror. The concave mirror forms a real image. A small, flat mirror then reflects the image to an eyepiece lens on the side of the tube. As in the refracting telescope, the eyepiece lens enlarges the image. 1. What are the two main parts of a refracting telescope? __________________________________________ 2. What is the purpose of each of these parts? ____________________________________________________ ___________________________________________________________________________________________ 3. What are the three main parts of a reflecting telescope? _________________________________________ ___________________________________________________________________________________________ 4. What is the function of each of these parts? ____________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 5. In what way are the refracting telescope and reflecting telescope similar? _________________________ ___________________________________________________________________________________________ 6. In what ways are the refracting telescope and reflecting telescope different? _______________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 13 Name Class Date 19-9 What is color? Lesson Review Explain how the terms in each pair are related. 1. prism, light _______________________________________________________________________________ 2. colors, visible spectrum ____________________________________________________________________ 3. wavelength, color _________________________________________________________________________ 4. red, wavelength ___________________________________________________________________________ 5. violet, wavelength _________________________________________________________________________ 6. prism, refract _____________________________________________________________________________ 7. absorbs, color _____________________________________________________________________________ 8. color, reflects _____________________________________________________________________________ 9. black, absorb ______________________________________________________________________________ 10. reflect, white ______________________________________________________________________________ Skill Challenge Skills: observing, analyzing, organizing In the table below, list ten objects that you see around you. Based on the color of each object, decide what color light the object absorbs and what color light the object reflects. Organize the information by completing the table. The first example is done for you. COLORS OF OBJECTS Object 1. Telephone Color Color(s) Absorbed Color(s) Reflected black all colors none 2. 3. 4. 5. 6. 7. 8. 9. 10. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 14 Name Class Date 19-10 How can light be used? Lesson Review Write true if the statement is true. If the statement is false, change the underlined term to make the statement true. Write your answers in the spaces provided. ____________________ 1. Optical fibers can be used for cutting, welding, and drilling. ____________________ 2. The use of optical fibers is called fiber optics. ____________________ 3. Laser light is made up of many wavelengths of light. ____________________ 4. Light travels through optical fibers quickly because it refracts repeatedly within the fiber. ____________________ 5. A beam of laser light cannot travel long distances in a straight line. ____________________ 6. White light is made up of many wavelengths. ____________________ 7. Doctors can attach cameras to optical fibers. ____________________ 8. Total internal reflection exists when light is repeatedly reflected within a given material. Skill Challenge Skills: organizing, identifying In the space below, construct a table that lists five familiar objects that either use or are made using fiber optics or lasers. Organize the table so that one area lists fiber optics, while the other lists lasers. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 15 Name THE Class Big IDEA Date Integrating Technology Chapter 19 How is light used in the home? Lesson Review Refer to the article, call outs, and Figure19-34 on pages 422 and 423 of your text to answer the following questions. 1. What is one way in which fiber optics can be used in home technologies? _________________________ ___________________________________________________________________________________________ 2. What kinds of light are used in a speed cook oven? _____________________________________________ ___________________________________________________________________________________________ 3. How do rooftop solar-heating panels work? ___________________________________________________ ___________________________________________________________________________________________ 4. What kind of light is used to play CDs? _______________________________________________________ 5. What kind of waves do motion detectors pick up? ______________________________________________ Skill Challenge Skill: inferring Which kinds of light-based technologies do you think will be found in homes in the future? ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Science Log Writing Activity Complete the Science Log on a separate sheet of paper. To complete the Big Idea Online, go to www.conceptsandchallenges.com. Follow the online instructions. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 16 Name Class Date Chapter 19 Key Term Review PART A Two of the statements below each term are correct. Circle the letters of the correct statements. 1. chlorophyll 3. lens a. green substance a. opaque material b. found in all organisms b. bends light c. found in plants c. transparent material 2. electromagnetic spectrum 4. eye a. includes radio waves a. sense organ b. includes visible light b. luminous object c. includes opaque objects c. detects light PART B Match each term in Column B with its definition in Column A. Write the correct letter in the space provided. Column B Column A __________ 1. the use of optical fibers a. sight __________ 2. objects that give off their own light b. regular reflection __________ 3. material that transmits light easily c. light __________ 4. reflection that forms an irregular image d. illuminated objects __________ 5. lens that curves outward e. transparent __________ 6. image that can be projected on a screen f. luminous objects __________ 7. reflection that forms a clear image g. fiber optics __________ 8. material that transmits some light h. diffuse reflection __________ 9. objects that reflect light i. opaque __________ 10. material that blocks light j. convex lens __________ 11. one of the five human senses k. laser __________ 12. lens that curves inward l. translucent __________ 13. light made up of only one wavelength m. real image __________ 14. form of electromagnetic energy made up of streams of photons n. concave lens Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 17 Name Class Date Chapter 19 Test Interpreting Diagrams Use the diagrams to answer the following questions. A B C D E F _________ 1. Which diagram shows a luminous object? __________ 2. Which diagram shows a concave lens? __________ 3. Which diagram shows an object that would appear black? __________ 4. Which diagram shows laser light? __________ 5. Which diagram shows a convex lens? __________ 6. Which diagram shows an object that would appear white? Multiple Choice Write the letter of the term or phrase that best completes each statement. __________ 1. A photon is a. an atom of light. c. a small bundle of energy. b. a visible molecule. d. a charged particle. __________ 2. Light waves travel fastest in a a. solid. b. liquid. c. gas. d. vacuum. __________ 3. An example of an illuminated object is a a. mirror. b. light bulb. c. campfire. d. flashlight. __________ 4. The clear, protective layer of the eye is the a. iris. b. lens. c. cornea. d. pupil. __________ 5. The color of light is determined by its a. speed. b. wavelength. c. amplitude. d. intensity. __________ 6. In order to make food, plants need a. heat. b. fertilizer. c. prisms. d. sunlight. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 18 Name Class Date Chapter 19 Test (continued) __________ 7. Electromagnetic waves a. do not have electrical properties. c. are made of two transverse waves. b. do not have magnetic properties. d. are made of four transverse waves. __________ 8. In regular reflection, the reflected image will be a. clear. b. fuzzy. c. distorted. d. upside down. __________ 9. An image that can be projected onto a screen is a a. virtual image. b. real image. c. false image. __________ 10. A concave lens a. curves inward. b. curves outward. d. true image. c. reflects light. d. absorbs light. __________ 11. The waves with the longest wavelength and the lowest frequency are a. infrared. b. ultraviolet. c. radio waves. d. X-rays. __________ 12. The waves with the shortest wavelength and the highest frequency are a. radio waves. b. gamma rays. c. X-rays. d. ultraviolet. __________ 13. Laser light a. includes all the colors of light. c. has waves that are not in step. b. travels in a curved line. d. does not spread out like white light. __________ 14. The height of a wave is called its a. frequency. b. amplitude. c. wavelength. d. speed. __________ 15. An example of an opaque object is a a. window. b. cardboard box. c. stained glass window. d. convex lens. __________ 16. The amount of light that enters the eye is controlled by the a. iris. b. retina. c. cornea. d. lens. __________ 17. The color that has the longest wavelength is a. blue. b. green. c. red. d. orange. __________ 18. If a beam of light strikes a mirror at a 30° angle, the angle of reflection will be a. 60°. b. 30°. c. 0°. d. 180°. Written Response Answer the following questions in complete sentences. 19. EXPLAIN: What is the process of photosynthesis and how does it work? _________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ 20. ANALYZE: What is light? What are some of its characteristics? __________________________________ ___________________________________________________________________________________________ ___________________________________________________________________________________________ Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 19 Answer Key CHAPTER 19: LIGHT 19-1 What is the electromagnetic spectrum? Lesson Review 1. b 2. d 3. f 4. c 5. g 6. e 7. h 8. a Skill Challenge 1. radio waves, microwaves, and infrared rays 2. gamma rays 3. violet 4. red 19-2 What is light? Lesson Review 1. electromagnetic 2. small bundles of energy 3. beam 4. energy, energy 5. straight 6. ray, straight line Skill Challenge 1. Electrical 2. Chemical 3. Heat 4. Heat, Electrical, and Mechanical 19-2 What is light? Enrichment Activity: Light Years 1. 81.7 trillion km 2. Proxima Centauri 3. about 8,550 trillion km 4. Polaris 5. 900 years ago 6. Yes, because the light from this star takes 520 years to reach Earth; Even if the star had been dead for hundreds of years, light that left the star 520 years ago would still be traveling toward Earth. 19-3 How do light waves travel? Lesson Review 1. true 2. transverse 3. do not need 4. true 5. true 6. a vacuum 7. wavelength 8. speed 9. amplitude 10. true Skill Challenge 1. wavelength 2. amplitude 3. left to right 4. up and down 5. transverse, because the particles of the medium are moving up and down at right angles to the direction the wave is traveling 19-3 How do light waves travel? Enrichment Activity: Speed of Light in Different Materials 1. diamond 2. vacuum 3. It slows down. 4. Yes; Light probably travels fastest in low-density materials and slowest in high-density materials because the materials, listed in the table are listed in order of increasing density and decreasing speed of light. 5. The light would slow down a lot as it enters the glass, speed up when it enters the water, speed up a little more when it enters the ice cube, slow down again when it enters the water, slow down even more when it enters the glass again, and then, speed up dramatically when it returns to the air. 19-4 What are sources of light? Lesson Review 1. c 2. d 3. e 4. f 5. a 6. b Skill Challenge 1. Transparent 2. Luminous 3. Translucent 4. Translucent 5. Opaque 6. Illuminated 7. Opaque 8. Translucent 9. Luminous 10. Translucent 19-4 What are sources of light? Enrichment Activity: Objects and Light 1. illuminated 2. luminous 3. transparent 4. translucent 5. opaque 6. illuminated 7. opaque 8. luminous 19-5 What is photosynthesis? Lesson review 1. food 2. chemical 3. leaves 4. chlorophyll 5. green 6. move to continue facing the Sun 7. electrical 8. chlorophyll in the leaves is green Skill Challenge 1. carbon dioxide, water, and energy from the Sun 2. sugar and oxygen 3. It enters through roots in the soil. Then, it travels up the stem to the leaf. 4. The source of carbon dioxide is the air; carbon dioxide enters through stomata on the underside of the leaf. 5. It is absorbed by the leaf. 6. through the stomata on the underside of the leaf Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 20 Answer Key 19-6 How do lenses refract light? 19-8 How do mirrors reflect light? Lesson Review 1. convex 2. bends or refracts 3. true 4. inward 5. true 6. concave 7. lens 8. true Skill Challenge Check students’ diagrams for accuracy. Enrichment Activity: Telescopes 1. objective lens and eyepiece lens 2. The objective lens focuses the light and forms a real image. The eyepiece lens makes the image larger and changes it to a virtual image. 3. concave mirror, flat mirror, and eyepiece lens 4. The concave mirror focuses the light and forms a real image. The flat mirror reflects the image to the eyepiece lens. The eyepiece lens makes the image larger. 5. Both use an eyepiece lens to make the image larger. 6. The reflecting telescope uses a concave mirror to focus light, while the refracting telescope uses a convex lens to focus light. In the reflecting telescope, a flat mirror reflects the image to the eyepiece lens, while in the refracting telescope, the image travels straight down the tube from the objective lens to the eyepiece lens. 1. convex lens 2. concave lens 19-7 How do you see? Lesson Review 1. clear layer that covers the front of the eye; protects the eye by keeping dirt and bacteria away from the inner parts of the eye 2. opening through which light enters the eye 3. It is a muscle that controls the amount of light that enters the eye. It expands or contracts depending on the amount of light that is available. 4. Light that enters the eye is focused by the lens onto the retina. 5. picture that is formed by the eye 6. It converts the image into electrical impulses. 7. It provides a path for electrical impulses from the retina to travel to the brain. 8. in the brain Skill Challenge 1. optic nerve 2. retina 3. cornea 4. lens 5. pupil 6. iris 19-8 How do mirrors reflect light? Lesson Review 1. D 2. R 3. D 4. R 5. R, D 6. D 7. R 8. D Skill Challenge 1. solid lines; dashed lines 2. Both sets are parallel. 3. angle a = angle of incidence; angle b = angle of reflection 4. 30° 5. They will all be 30°. 6. solid lines; dashed lines 7. Only the set of solid lines is parallel. 8. regular; diffuse 9. In regular reflection, incident rays are parallel and reflected rays are parallel. In diffuse reflection, incident rays are parallel and reflected rays are not parallel. 10. In regular reflection, all light will be reflected at the same angle. In diffuse reflection, the light will be reflected at different angles. 19-9 What is color? Lesson Review Possible answers: 1. A prism is a triangular piece of glass that separates white light into a band of colors. 2. The seven colors that make up white light are called the visible spectrum. 3. The wavelength of light determines its color. 4. Red light has the longest wavelength. 5. Violet light has the shortest wavelength. 6. A prism refracts a beam of light. 7. An object absorbs all colors except the color it reflects. 8. An object appears the color that it reflects. 9. Objects that absorb all colors of light appear black. 10. Objects that reflect all colors of light appear white. Skill Challenge Check students’ tables to make sure that they understand that the color they see is the one that is reflected from the object, not the color that is absorbed by it. Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 21 Answer Key 19-10 How can light be used? Lesson Review 1. Lasers 2. true 3. one wavelength 4. reflects 5. can 6. true 7. true 8. true Skill Challenge Check students’ tables to make sure that they are organized logically and that objects listed involve either lasers or fiber optics. Possible answers: Lasers: CD player, DVD player, supermarket scanner, medical devices, and industrial tools Optical fibers: phone cables, TV cables, computer networks, and medical devices The Big Idea Lesson Review 1. Fiber optics can be used in telephone lines in the home 2. visible and infrared light 3. convert sunlight into thermal energy for heating air and water 4. laser light. 5. infrared waves Skill Challenge Possible answers: Fiber-optic cables will probably play a larger role in receiving not only telephone calls but computer information and TV signals; solar heating may become more popular; speed cook ovens will probably become more popular. CHAPTER 19: LIGHT Chapter Test Interpreting Diagrams 1. C 2. A 3. E 4. D 5. B 6. F Multiple Choice 1. c 2. d 3. a 4. c 5. b 6. d 7. c 8. a 9. b 10. a 11. c 12. b 13. d 14. b 15. b 16. a 17. c 18. b Written Response 19. Photosynthesis is the process whereby plants make food from sunlight, carbon dioxide, and water. In the process, plants give off oxygen. Chlorophyll, which is a green substance located mostly in the leaves, absorbs sunlight and enables photosynthesis to occur. 20. Light is a form of electromagnetic energy that sometimes behaves as if it is an electromagnetic wave, and sometimes behaves as if it is made up of tiny particles of energy called photons. It is made up of many wavelengths, and can have varying levels of energy associated with it. It has a speed of about 300,000 km/s in a vacuum. CHAPTER 19: LIGHT Key Term Review PART A 1. a, c 2. a, b 3. b, c 4. a, c PART B 1. g 2. f 3. e 4. h 5. j 6. m 7. b 8. l 9. d 10. i 11. a 12. n 13. k 14. c Concepts and Challenges in Physical Science, Teacher’s Resources CD-ROM (c) by Pearson Education, Inc./Globe Fearon/Pearson Learning Group. All rights reserved. Light: CHAPTER 19, page 22