Using Light guide-double - Infobase

Teacher’s Guide

High/Middle

School

Editors:Brian A. Jerome, Ph.D.Stephanie Zak Jerome

Assistant Editor:Anneliese Brown

Using Light

Visual Learning CompanyBrandon, Vermont

1-800-453-8481www.visuallearningco.com

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Visual Learning Company 1-800-453-8481

Reviewers:Reviewers:Reviewers:Reviewers:Reviewers:Reviewers:Linda ArnoneClark County Public SchoolLas Vegas, Nevada

Steve WelchRutland Middle SchoolRutland, Vermont

John PetersonProfessor Emeritus of PhysicsProvidence, Rhode Island

Use and Copyright:Use and Copyright:Use and Copyright:Use and Copyright:Use and Copyright:The purchase of this video program entitles the user the right to reproduce orduplicate, in whole or in part, this teacher’s guide and the blackline masterhandouts for the purpose of teaching in conjunction with this video, UsingLight. The right is restricted only for use with this video program. Anyreproduction or duplication, in whole or in part, of this guide and the studentmasters for any purpose other than for use with this video program isprohibited.

The video and this teacher’s guide are the exclusive property ofthe copyright holder. Copying, transmitting or reproducing inany form, or by any means, without prior written permissionfrom the copyright holder is prohibited (Title 17, U.S. CodeSections 501 and 506).

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The video and accompanying teacher’s guide are forinstructional use only. In showing these programs, noadmission charges are to be incurred. The programs are to beutilized in face-to-face classroom instructional settings,library settings, or similar instructional settings.

Duplication rights are available, but must be negotiated withthe Visual Learning Company.

Television, cable, or satellite rights are also available, butmust be negotiated with the Visual Learning Company.

Closed circuit rights are available, and are defined as the useof the program beyond a single classroom but within a singlecampus. Institutions that wish to utilize the program inmultiple campuses must purchase the multiple campus versionof the program, available at a slightly higher fee.

Discounts may be granted to institutions interested inpurchasing programs in large quantities. These discounts maybe negotiated with the Visual Learning Company.

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Table ofTable ofTable ofTable ofTable ofContentsContentsContentsContentsContents

National Standards Correlations 6

Student Learning Objectives 7

Assessment 8

Introducing the Video 9

Video Viewing Suggestions 9

Video Script 11

Answers to Student Assessments 16

Page

Answers to Student Activities 17

Assessment and Student Activities Masters 18

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A Message from our A Message from our A Message from our A Message from our A Message from our Company . . . Company . . . Company . . . Company . . . Company . . .Dear Educator:

Thank you for your interest in the educational videos produced by theVisual Learning Company. We are a Vermont-based, family owned andoperated business specializing in the production of quality educationalscience videos and materials.

We have a long family tradition of education. Our grandmothers graduatedfrom normal school in the 1920’s to become teachers. Brian’s mother wasan elementary teacher and guidance counselor, and his father was a highschool teacher and superintendent. This family tradition inspired Brian tobecome a science teacher and to earn a Ph.D. in education, and leadStephanie to work on science educational programs at NASA.

In developing this video, accompanying teacher’s guide, and studentactivities, our goal is to provide educators with the highest quality materials,thus enabling students to be successful. In this era of more demandingstandards and assessment requirements, supplementary materials need to becurricular and standards based - this is what we do!

Our videos and accompanying materials focus on the key concepts andvocabulary required by national and state standards and goals. It is ourmission to help students meet these goals and standards, while experiencingthe joy and thrill of science.

Sincerely,

Brian and Stephanie Jerome

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National StandardsNational StandardsNational StandardsNational StandardsNational StandardsCorrelationsCorrelationsCorrelationsCorrelationsCorrelationsNational Science Education StandardsNational Science Education StandardsNational Science Education StandardsNational Science Education StandardsNational Science Education Standards(Content Standards: 5-8, National Academy of Sciences, c. 1996)

Benchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science LiteracyBenchmarks for Science Literacy(Project 2061 - AAAS, c. 1993)

Science as Inquiry - Content Standard A:As a result of activities in grades 5-8, all students should develop:• Abilities necessary to do scientific inquiry• Understandings about scientific inquiry

Physical Science - Content Standard B:As a result of their activities in grades 5-8, all students should developan understanding of how:• Light interacts with matter by transmission (including refraction). To see an object, light from the object - emitted by or scattered from it - must enter the eye.

The Physical Setting - Motion (4F)By the end of the 8th grade, students should know that:• Light from the sun is made up of a mixture of many different colors

of light, even though to the eye the light looks almost white. Otherthings that give off or reflect light have a different mix of colors.

• Something can be “seen” when light waves emitted or reflected byit enter the eye.

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Student LearningStudent LearningStudent LearningStudent LearningStudent LearningObjectivesObjectivesObjectivesObjectivesObjectives

Upon viewing the video and completing the enclosed studentactivities, students should be able to do the following:

• Define and explain the processes of reflection, diffraction, and refraction;

• Differentiate between transparent, translucent, and opaque objects;

• Explain how the processes of reflection and absorption affectthe colors we see in objects;

• Understand that white reflects all colors of the spectrum, and that black absorbs all colors of the spectrum;

• Explain how polarized lenses, including polarized sunglasses, reduce glare;

• Describe the Law of Reflection utilizing the terms angle ofincidence and angle of reflection;

• Identify and describe the characteristics of plane mirrors, concave mirrors, and convex mirrors; and

• Describe the characteristics and some of the uses of concaveand convex lenses.

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AssessmentAssessmentAssessmentAssessmentAssessment

Preliminary Test:Preliminary Test:Preliminary Test:Preliminary Test:Preliminary Test:

Video Review:Video Review:Video Review:Video Review:Video Review:

Post-Test:Post-Test:Post-Test:Post-Test:Post-Test:

The Preliminary Test, provided in the Student Masters section, is anassessment tool designed to gain an understanding of student preexistingknowledge. It can also be used as a benchmark upon which to assessstudent progress based on the objectives stated on the previous pages.

The Video Review, provided in the Student Masters section, can be used asan assessment tool or as a student activity. There are two main parts. Thefirst part contains questions titled “You Decide” that can be answered duringthe video. The second series of ten questions consists of a video quiz to beanswered at the conclusion of the video.

The Post-Test, provided in the Student Masters section, can be utilized as anassessment tool following student completion of the video and studentactivities. The results of the Post-Test can be compared against the results ofthe Preliminary Test to assess student progress.

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Video ViewingVideo ViewingVideo ViewingVideo ViewingVideo ViewingSuggestionsSuggestionsSuggestionsSuggestionsSuggestionsYou may want to photocopy and distribute the Student Master, “VideoReview.” You may choose to have your students complete this Master whileviewing the program or to do so upon its conclusion.

The program is approximately 20-minutes in length and includes a ten-question video quiz. Answers are not provided to the Video Quiz on thevideo, but are included in this teacher’s guide. You may decide to eithergrade student quizzes as an assessment tool or to review the answers inclass.

The video is content-rich with numerous vocabulary words. For this reasonyou may want to periodically stop the video to review and discuss newterminology and concepts.

Introducing theIntroducing theIntroducing theIntroducing theIntroducing theVideoVideoVideoVideoVideo

We use light nearly every waking moment. From the time we wake up inthe morning until the time we go to sleep, we use light to navigate, read, dowork and recreate. Before showing the video, ask students to create a list ofsome of the ways they have used light today. Next, ask them to name somedifferent sources of light. This list may include such things as the sun, lightbulbs, fire, and television. You may also want to ask students about someways we manipulate light to improve our lives. Examples include mirrors,eyeglasses and the lights on vehicles. Tell students to carefully watch thevideo for examples of how light enables us to see color, and how light canbe manipulated by humans.

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Student AssessmentsStudent AssessmentsStudent AssessmentsStudent AssessmentsStudent Assessmentsand Activitiesand Activitiesand Activitiesand Activitiesand Activities

Assessment Masters:Assessment Masters:Assessment Masters:Assessment Masters:Assessment Masters:

Student Activity Masters:Student Activity Masters:Student Activity Masters:Student Activity Masters:Student Activity Masters:

• Preliminary Test

• Video Review

• Post-Test

• Mirror Images

• Reappearing Pennies

• Flashlight Physics

• Understanding Optics

• Vocabulary of Using Light

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1. One of the first ways children learn to describe their world is through the use of colors.

2. We know that the sky behind these geese appears blue,...

3. ...and that this jacket appears red...

4. . . . and that this sunset appears orange.

5. But where do colors come from?

6. How do our eyes receive and process color?

7. And what role does light play in enabling us to see color?

8. During the next few minutes we’re going to explore these questions about color,...

9. . . . while also taking a look at some of the properties of light, and . . .

10. . . . the way it interacts with matter.

11. Graphic Transition – Light in Action

12. The rays of the sun bouncing off the surface of this lake are blinding.

13. As is the light from this mirror.

14. You Decide!

What’s the term used to describe the process of light bouncing off objects?

15. That’s right, reflection. This is the process of light bouncing off objects. This ice is

reflecting the bright rays of the sun.

16. Shiny surfaces, such as ice and water, can reflect a large amount of the light that

strikes them.

17. Light is not only reflected, but can also be transmitted or absorbed.

18. (Sound of hammer breaking glass)

19. Glass is a breakable material that allows light, but not objects, to pass through it.

20. A substance such as clear water allows most light to pass through, allowing us to see

this purple starfish. The water is said to be transparent.

21. You Decide!

What is the difference between this plastic wrap and this wax paper?

22. This plastic wrap is transparent, allowing most of the light to pass through it, which

enables us to clearly see the fruit in the bowl.

23. The wax paper is not transparent, but instead is translucent.

24. Translucent materials only allow some light to pass through them. Translucent

materials scatter light.

25. Many plastics are translucent,...

26. . . . as are these curtains, allowing some light to pass through. The objects behind

them cannot clearly be seen.

27. In the case of this duck, it is neither transparent nor translucent. It’s opaque.

28. It is not possible to see through opaque objects.

29. Opaque objects tend to absorb some light and reflect some light.

Video Script-Video Script-Video Script-Video Script-Video Script-Using LightUsing LightUsing LightUsing LightUsing Light

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30. This helps explain how we see the color in objects. Let’s take a closer

look at color.

31. Graphic Transition - Color

32. The mountains seen here in early summer are a sea of green.

33. What causes this green color?

34. Millions of green leaves give these hills their green color. The sun produces light in a

variety of colors, including red, orange, yellow, green, blue, indigo and violet.

35. Green leaves absorb many of the colors coming from the sun.

36. Plants use these wavelengths of color along with other electromagnetic energy to

make food via the process of photosynthesis.

37. But leaves do not absorb green light.

38. Instead, green is reflected back and is the color we usually see the most when

looking at a plant.

39. The brilliant color of this bright red car behaves similarly.

40. The car absorbs all of the colors of the spectrum, except red, which it reflects.

41. On the other hand, this black car does not reflect any of the colors. Instead, black

absorbs all colors. Black is produced when the colors of the spectrum are absorbed.

42. You may have noticed that black objects, such as this road, tend to get warm during

sunny weather. That is partly due to the fact that black absorbs all of the colors of the

light spectrum.

43. The opposite holds true of white. White reflects all of the colors in the spectrum

44. And that is why it is a good idea to wear white in warm weather, to help keep the

body cooler.

45. Graphic Transition - Polarized Light

46. Goggles are helping this skier see the terrain as she speeds down the slope.

47. This fisherman is wearing sunglasses. Without them, the glare off the water’s surface

would be too intense to see the fish.

48. These sunglasses are specially designed to filter light. They are called polarizing

sunglasses.

49. Polarizing filters, including sunglasses, have many tiny parallel slits that have the

ability to reduce vibrating light that contributes to glare.

50. They kind of act like venetian blinds, with many parallel slits allowing planes of light

to pass through.

51. The light that passes through polarizing filters is called polarized light.

52. Notice how the polarized light that has passed through the filter is vibrating along a

single plane. This helps reduce glare.

53. Graphic Transition - Light Interactions

54. As we already mentioned, light can be absorbed or reflected. Look at the shape of

this pencil as it passes down into the glass of water.

55. You Decide!

What property of light causes this pencil to look as if it is bending?

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56. The answer is refraction. The property of light that makes objects look

differently in water is called refraction.

57. Refraction occurs when light passes from one medium to another. As light

passes from air into water, it slows down, causing it to bend when it strikes the

surface at an angle.

58. The bending of light causes the pencil to appear as if it is bent.

59. Refraction also causes objects under water to look bigger . . .

60. . .. than they actually are.

61. Diffraction is another property of light. Diffraction is the bending of light waves

around the edge of an object.

62. The process of diffraction is similar to the water in this stream bending around this

rock.

63. Diffraction is part of the reason you see the lights of an oncoming car before you

actually see the car.

64. Diffraction also is part of the reason the morning sky appears lit before the sun

actually rises over the horizon.

65. Graphic Transition - Reflection and Mirrors

66. This smooth lake surface shows a near perfect image of the bird flying over it.

67. And the rear view mirror in this car helps the driver to see what is behind her.

68. These objects are reflecting light. As we already mentioned, reflection occurs when

a wave hits an object and then bounces off it.

69. Light behaves like a ball bouncing on a flat surface.

70. When a ball hits a surface head on at a right angle, it bounces back in a straight line.

71. But if it hits at an angle, it bounces away at an equal angle.

72. Light behaves in a similar way.

73. For example, when light from this laser light hits this mirror at an angle, it bounces

or reflects away at an equal angle.

74. The light rays approaching a surface are called incident rays . . .

75. . . . and the light rays bouncing off a surface are called reflected rays.

76. The angle at which light strikes an object is called the angle of incidence.

77. And the angle at which light bounces off an object is called the angle of reflection.

78. The Law of Reflection states that the angle of incidence and the angle of reflection

are equal to each other.

79. Light, however, does not always reflect regularly, as we have just seen.

80. Regular reflection only occurs on very smooth surfaces, such as mirrors.

81. In most cases, a type of reflection called diffuse reflection occurs.

82. Most objects have an irregular surface. This brick wall, for example, when viewed

closely, has many bumps and pits.

83. When light strikes surfaces like these, it is scattered irregularly.

84. The atmosphere scatters light from the sun diffusely.


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85. This is because the atmosphere is filled with gases and dust particles that

scatter light, allowing us to see objects that are not directly hit by the sun’s

rays.

86. Graphic Transition - Mirrors and Light

87. There are a wide variety of mirrors.

88. Mirrors are categorized based on the shape of their surface.

89. They include plane mirrors, concave mirrors, and convex mirrors.

90. Let’s first take a look at mirrors that you are probably most familiar with - plane

mirrors.

91. A plane mirror has a perfectly flat surface.

92. The reflection of objects in a plane mirror appear their actual size and are right side

up.

93. However, the image is reversed.

94. Let’s take an example. If you raise your right hand while looking into a mirror, it

appears that the left hand of your reflection is raised.

95. Also, when you place words in front of a mirror, they are reversed.

96. You Decide!

Why is the word ambulance written backwards on the front of this ambulance?

97. It is written backwards so drivers can see the word correctly when they look in their

rear view mirror, and can then make room for the ambulance to pass.

98. Graphic Transition - Concave Mirrors

99. Have you ever seen your reflection in a spoon? A spoon is a type of concave mirror.

100. A concave mirror is a type of mirror in which the surface curves inward.

101. Concave mirrors are very useful in telescopes, helping to gather light from objects in

space.

102. Light rays coming in parallel to a concave mirror are reflected toward and through

the same point called a focal point.

103. In turn, light reflected by a concave mirror from a light source positioned at its focal

point reflects light rays parallel to one another.

104. Concave mirrors are useful in car headlights, helping to form a powerful light beam.

105. The same holds true in flashlights. Behind the bulb is a concave mirror.

106. The concave mirror helps to form a strong focused beam of light.

107. Graphic Transition - Convex Mirrors

108. Back to our spoon. If we flip the spoon over, it now forms a convex mirror.

109. A convex mirror curves outward.

110. In convex mirrors, the image appears smaller than the actual object.

111. Quite often the side mirrors on cars . . .

112. . . . and motorcycles are convex mirrors.

113. They are useful because they provide a wide field of view.


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114. You may even have seen convex mirrors in stores so that store

employees can see down aisles.

115. Graphic Transition - Concave and Convex Lenses

116. This thin piece of glass is a lens. Lenses are used in a variety of objects

such as eyeglasses.

117. Other lenses, such as these, are used in cameras.

118. A lens is a transparent material that bends light.

119. Most lenses, such as this camera lens, are made of glass or...

120. . . . plastic.

121. There are two main kinds of lenses - concave lenses and convex lenses.

122. Concave lenses are thinner in the middle and thicker at the edges.

123. Convex lenses are thicker at the center than at the edges.

124. This magnifying glass uses a convex lens and makes objects appear larger than they

actually are.

125. Graphic Transition - Summing Up

126. During the past few minutes we have explored many of the different properties of

light.

127. We have seen how objects reflect light,. . .

128. ...and absorb light,...

129. ...as well as how light can be refracted or...

130. . . . diffracted.

131. We also took a look at the characteristics of concave mirrors . . .

132. . . . and convex mirrors,...

133. ...as well as concave and convex lenses.

134. So the next time you notice the color of an object or use a mirror, think about the

properties of light. You just might think about light a little differently.

Video Quiz

Fill in the correct word when you hear this tone _______. Good luck, and let’s get

started.

1. __________ is the process of light bouncing off objects.

2. ____________ objects allow light to easily pass through them.

3. ___________ objects absorb most light.

4. ___________ reflects all the colors of the spectrum.

5. _________ filters reduce glare.

6. The process that causes the pencil to look as if it is bending is __________.

7. Light rays approaching an object are called _________ rays.

8. A _________ reflection occurs off an irregular surface.

9. This is an image of a _____ mirror.

10. Convex mirrors provide a ________ field of view.


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Answers toAnswers toAnswers toAnswers toAnswers toStudent AssessmentsStudent AssessmentsStudent AssessmentsStudent AssessmentsStudent Assessments

Preliminary Test1. transparent2. refraction3. diffraction4. absorbed5. concave6. reflection7. opaque8. diffuse9. plane10. shiny11. true12. false13. true14. true15. false16. true17. true18. false19. false20. true

Video ReviewYou Decide:A. reflectionB. Plastic wrap is transparent, while waxpaper is translucent.C. refractionD. The word is written backwards so thatdrivers can read it when they look in theirrearview mirrors, allowing them to makeroom for the ambulance to pass.

Post Test1. false2. true3. false4. true5. true6. true7. false8. true9. true10. false11. diffraction12. transparent13. shiny14. refraction15. opaque16. reflection17. absorbed18. plane19. concave20. diffuse

Video Quiz:1. reflection2. transparent3. opaque4. white5. polarizing6. refraction7. incident8. diffuse9. concave10. wide

Answers to StudentAnswers to StudentAnswers to StudentAnswers to StudentAnswers to StudentActivitiesActivitiesActivitiesActivitiesActivities

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Mirror ImagesConclusions: In the convex mirror, the tree’sreflection is upright and smaller. If the tree’sreflection in the concave mirror is uprightand larger, the reflection is within the focalpoint. If the reflection is upside down andsmaller, it is beyond the focal point. Answerswill vary.

.

Understanding Optics1. Eye specialists use the principles ofrefraction to determine how much moreor less light rays need to be bent in orderfor vision to be clear. This measurementhelps to determine the prescription of thelenses.2. Nearsightedness results when lightrays focus before meeting the retina.This affects the ability to see distantobjects, but close objects remain clear.3. Farsightedness results when light raysreach the retina before focusing. Thisaffects the ability to see close objects, butdistant objects remain clear.4. Nearsightedness - Diagram A Farsightedness - Diagram B5. concave6. convex7. Answers will vary.

Vocabulary Lesson1. diffraction, g2. translucent, c3. concave, d4. polarizing, j5. lens, i6. refraction, e7. reflection, a8. convex, f9. incidence, h10. transparent, b

Reappearing PenniesConclusions: Refraction causes the penny toreappear. The water slows the light and bendsit, allowing the penny to be seen. The pennyalso appears larger because the water bendsthe light. The penny near the back of theglass looks larger because the light musttravel through more water, creating a largerimage.

Flashlight PhysicsConclusions: In step 4, the distances shouldbe relatively equal. The distances would notbe equal if the students were of differentheights. In step 5, the partner with theflashlight will be closer to the mirror than his/her partner. It is not possible to produce astrong, reflected beam of light with thealuminum foil. This is because unevensurfaces scatter light, resulting in diffusereflection. The ball would not bounce off atthe expected angle and would therefore missits target.


AssessmentAssessmentAssessmentAssessmentAssessmentand Studentand Studentand Studentand Studentand Student

Activity Activity Activity Activity Activity Masters Masters Masters Masters Masters

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Using LightName___________________

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Preliminary TestPreliminary TestPreliminary TestPreliminary TestPreliminary Test

1. Materials such as glass and water are _________, allowing most light to pass through them.

2. __________ occurs when light passes from one medium to another, causing the light to speed up or slow down.

3. _________ is the bending of light waves around the edge of an object.

4. Black is produced when all the colors of the spectrum are _________.

5. _________ lenses are thinner in the middle and thicker at the edges.

6. The angle at which light bounces off an object is called the angle of _________.

7. _________ objects tend to absorb some light and reflect the rest.

8. In _________ reflection, light is scattered after hitting irregular surfaces.

9. A ________ mirror has a perfectly flat surface.

10. _________ surfaces reflect a large amount of the light that strikes them.

shinytransparentopaquerefractiondiffractionreflection

absorbedplaneconcavediffuseincidenceconvex

Directions: Fill in the blank with the correct word. A list ofpossible answers is provided at the bottom of the page.


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PreliminaryPreliminaryPreliminaryPreliminaryPreliminaryTestTestTestTestTestDirections: Decide whether the answer is True (T) or False (F).

T F

T F

11. Reflection is the process of light bouncing off objects.

12. Opaque objects allow most light to pass through them.

13. Leaves do not absorb most green light.

14. White reflects all of the colors in the spectrum.

15. Refraction causes objects under water to appear smaller than they actually are.

16. The Law of Reflection states that the angle of incidence and the angle of reflection are equal to each other.

17. The image in a plane mirror is reversed.

18. In convex mirrors, the image appears larger than the actual object.

19. Concave lenses are thicker in the middle and thinner at the edges.

20. After passing through a filter, polarized light vibrates along a single plane.

T F

T F

T F

T F

T F

T F

T F

T F


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Video ReviewVideo ReviewVideo ReviewVideo ReviewVideo Review

You Decide:

A. What’s the term used to describe the process

of light bouncing off objects?

B. What is the difference between this plastic

wrap and this wax paper?

C. What property of light causes this pencil to

look as if it is bending?

D. Why is the word AMBULANCE written

backwards on the front of this ambulance?

Directions: During the course of the video, answer the “You Decide”

questions as they appear. Answer the Video Quiz questions at the end of

the video.

Answer: _______________

Answer: _______________

Answer: _______________

Answer: _______________

Video Quiz:1. ___________ is the process of light bouncing off objects.

2. __________ objects allow light to easily pass through them.

3. __________ objects absorb most light.

4. __________ reflects all the colors of the spectrum.

5. __________ filters reduce glare.

6. The process that causes the pencil to look as if it is bending is __________.

7. Light rays approaching an object are called __________ rays.

8. A __________ reflection occurs off an irregular surface.

9. This is an image of a __________ mirror.

10. Convex mirrors provide a __________ field of view.


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Post TestPost TestPost TestPost TestPost Test

Directions: Decide whether the answer is True (T) or False (F).

1. Concave lenses are thicker in the middle and thinner at the edges.

2. Leaves do not absorb most green light.

3. Opaque objects allow most light to pass through them.

4. After passing through a filter, polarized light vibrates along a single plane.

5. White reflects all of the colors in the spectrum.

6. The image in a plane mirror is reversed.

7. Refraction causes objects under water to appear smaller than they actually are.

8. Reflection is the process of light bouncing off objects.

9. The Law of Reflection states that the angle of incidence and the angle of reflection are equal to each other.

10. In convex mirrors, the image appears larger than the actual object.

T F

T F

T F

T F

T F

T F

T F

T F

T F

T F


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Post TestPost TestPost TestPost TestPost TestDirections: Fill in the blank with the correct word. A list ofpossible answers is provided at the bottom of the page.

11. _________ is the bending of light waves around the edge of an object.

12. Materials such as glass and water are _________, allowing most light to pass through them.

13. _________ surfaces reflect a large amount of the light that strikes them.

14. __________ occurs when light passes from one medium to another, causing the light to speed up or slow down.

15. _________ objects tend to absorb some light and reflect the rest.

16. The angle at which light bounces off an object is called the angle of _________.

17. Black is produced when all the colors of the spectrum are ________.

18. A ________ mirror has a perfectly flat surface.

19. _________ lenses are thin in the middle and thick at the edges.

20. In ________ reflection, light is scattered after hitting irregular surfaces.

shinytransparentopaquerefractiondiffractionreflection

absorbedplaneconcavediffuseincidenceconvex


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Mirror ImagesMirror ImagesMirror ImagesMirror ImagesMirror ImagesObjective: In this lab you will learn about the properties of plane, convex,and concave mirrors.

Background: Mirrors are an important part of our everyday lives. They enable us todrive our cars safely, check our appearances, and view the stars. Most of the mirrors thathang on the walls of our homes are plane mirrors. Plane mirrors are perfectly flat,producing images that are upright and the same size as the object. The images, however,are reversed. For example, if you blink your right eye when looking in a mirror, itappears as though the left eye of your reflection is blinking. But not all mirrors producethese types of images. As you have learned, the size and orientation of the reflectedimage depends on the shape of the mirror. A mirror that curves outward is a convexmirror, bending the light so that the image is upright and smaller than the actual object.Convex mirrors widen our field of vision and are therefore used in rearview mirrors. Amirror that is curved inward, like a spoon, is a concave mirror. The distance betweenthe object and mirror determines the size and orientation of the image. Light rays comingin parallel to a concave mirror are reflected through the same point, called the focalpoint. If the object is within the focal point, the image appears upright and is larger thanthe object. If the object is located beyond the focal point, the image appears upside downand smaller than the object. Concave mirrors are used in telescopes to gather light fromobjects in space, thus allowing us to see things that are invisible to the naked eye.

Materials:Concave mirrorConvex mirrorPlane mirrorSheet of paperPen or pencil

Directions:1. Send a coded message to a classmate. Write a word or message that can only be read by seeing its reflection in a plane mirror. This is tricky, so practice to see which way the letters need to be oriented in order for their reflection to be readable.2. Draw a picture of a tree on a separate sheet of paper.3. Hold the drawing in front of a convex mirror. Record the size and position of the tree’s reflection.4. Repeat Step 3 using a concave mirror..

Conclusion: How did the tree appear in the convex mirror? How did it appear in theconcave mirror? Based on its appearance in the concave mirror, was the tree locatedwithin or beyond the focal point? Brainstorm a list of five different everyday uses ofmirrors. Determine whether the mirrors are concave, convex or plane mirrors.


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Reappearing PenniesReappearing PenniesReappearing PenniesReappearing PenniesReappearing PenniesObjective: In this lab you will observe the refraction of light.

Background: Did you know that objects underwater, such as fish orseashells, are actually smaller than they appear? This occurs because of refraction.Refraction is the same phenomenon that causes a pencil partially submerged inwater to appear as if it is bent. Refraction, or the bending of light, occurs whenlight passes from one medium to another. When travelling through air, lightmoves at a constant speed. The speed of light waves decreases when they enter asubstance of a different density, causing them to bend. After passing through thematerial, the light rays return to the original speed and direction in which theywere traveling before encountering the denser material. Refraction is part of oureveryday lives - it is what enables eyeglasses and contacts to correct vision, andcauses prisms to produce beautiful rainbows of colors.

Materials:PennyOpaque cupDry erase marker

Directions:1. Your teacher will divide you into groups of two.2. Place the penny in the opaque cup.3. Keeping your eye on the penny, have your partner slowly move the cup away from you. Tell him or her to stop once you can no longer see the penny.4. Have your partner slowly pour water into the cup. Tell him or her to stop when the penny reappears.5. Switch places with your partner. Repeat steps 3 & 4.6. Tie a piece of string around a penny. Secure it with a piece of tape if necessary.7. Submerge the penny in the clear glass filled with water. Place it near the front of the glass.8. Looking through the side of the glass, draw the image of the penny on the glass. Compare your drawing to a penny that is not submerged in water.9. Now place the penny toward the back of the glass. Repeat step 8.

Conclusion: What property of light causes the penny to reappear? Explain whythis occurs. In step 8, does the penny appear larger or smaller than an actualpenny? Why does this occur? Which produces a larger image of the penny,placing it near the front or the back of the glass? Explain.

Clear glass filled with waterStringTape


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Flashlight PhysicsFlashlight PhysicsFlashlight PhysicsFlashlight PhysicsFlashlight PhysicsBackground:Have you ever watched someone play pool and been amazed by some ofthe shots they can make? When there is no clear shot, it is often necessary tobounce the ball off the side walls of the pool table. One of the secrets tobecoming a pool shark is to know that the ball will bounce off the wall at thesame angle at which it hit the wall. This is similar to the reflection of light. Asyou know, reflection is the process of light bouncing back. The angle at whichlight hits an object is called the angle of incidence, while the angle at which lightbounces off an object is called the angle of reflection. According to the Law ofReflection, the angle of incidence equals the angle of reflection. The angle atwhich light bounces off the surface is equal to the angle at which it hits thesurface, following the same rule as the pool ball.

Objective: In this lab you will learn about the Law of Reflection.

Materials:FlashlightMeter stick

Directions:1. Your teacher will pair you with a classmate of the same height.2. Stand 2-3 feet away from your partner, facing him or her.3. Place a mirror on the floor between you and your partner. Turn off the lights.4. One partner should hold the flashlight by his or her nose and shine it on the mirror. The partner with the flashlight should move back and forth until the reflection of the beam hits the other student’s nose. Measure the distance each student is standing from the center of the mirror.5. Repeat Step 4 after switching roles. This time, the student with the flashlight should be on his or her knees, while the other student remains standing. Once the light has hit the partner’s nose, measure how far each student is from the mirror.6. Replace the mirror with a piece of aluminum foil that has been crumpled and unfolded again (but not smoothed). Repeat Step 4.Discussion:Compare the distance each partner stands from the mirror in Step 4. Would thedistances be different from one another if the shortest and tallest students werepaired together? How do these distances compare in Step 5? What happenedwhen you replaced the mirror with the wrinkled aluminum foil? Discuss withyour partner why you think this occurred. What would happen to a pool ball if amanufacturing flaw in the pool table produced a bump on the side wall?

Mirror (at least 6 x 6 inches)Piece of aluminum paper (same size)


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Understanding OpticsUnderstanding OpticsUnderstanding OpticsUnderstanding OpticsUnderstanding OpticsObjective: In this lab you will learn how different properties of lightaffect vision.

Directions: Answer the questions based on the information provided below.

Background: Have you ever wondered how your eyes enable you to see? Youmay be surprised to discover that many of the light properties that you havelearned about play an important role in vision. For those with so-called perfectvision, light rays enter the eye and converge, or focus, at a point directly on theretina, which is the tissue lining the back of the eyeball. This can be seen in thediagram below.

However, only 40% of the population has perfect vision. This means that if youhave a group of ten people, only four of them will be able to see perfectlywithout the aid of glasses or contact lenses. The other six people will have an eyedisorder, such as nearsightedness or farsightedness. Eyeglasses, contact lenses, orcorrective surgery enable people to see clearly despite these disorders.Nearsightedness, or myopia, means that you can see objects which are close butnot objects at a distance. This occurs when the eyeball is too long from front toback, causing light rays from distant objects to focus before reaching the retina.When light rays finally reach the retina, they produce a blurred image.Nearsighted people are able to clearly see distant objects with the aid of concavelenses. Concave lenses are thinner in the middle than at the edges, causing themto bend the light rays outward so that they focus on the retina.

Retina


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at the edges. Convex lenses bend the light rays inward, enabling them to focus onthe retina, making close-range objects appear clearly. Fortunately, people with eye disorders are able to see clearly with the aid of eyeglasses or contact lenses. The lenses of eyeglasses are ground to form eitherconcave or convex lenses, although it is often necessary to use a combination ofthe two. Many people have blurred vision when viewing both distant andclose-range objects. These people rely on bifocal or trifocal lenses to see clearly.The lenses of bifocal glasses are assembled so that they have both convex andconcave parts, one on top of the other. Trifocals have a center part that allows youto see intermediate distances. Many people find it convenient to wear contactlenses, which are plastic corrective lenses. They are held in place by a thin layerof tears on the eye’s surface. Although it appears as though contact lenses have adramatic concave shape, they can be either concave or convex lenses, thusenabling both nearsighted and farsighted people to see clearly. So how do you find out if you have an eye disorder? Many people go to an eyespecialist for an eye exam. During the part of the exam known as refraction, youreye specialist measures how much more or less each eye needs to refract light raysso that they focus on the retina. This measurement helps the specialist determineyour eye prescription. As you can see, your vision is just one of the many waysthat light makes a difference in your everyday life.

Questions:

1. How does the refraction of light affect vision?

2. What happens if your eye is too long from front to back?

3. What happens if your eye is too short from front to back?

Farsightedness, or hyperopia, means that you can clearly see distant objects butnot objects at a close range. This occurs when the eyes are too short. If there wereno physical barriers, light rays would converge behind the retina. Although this isnot physically possible, the light rays strike the retina before they are brought into focus, making close objects appear blurred. The ability to see close-rangeobjects can be improved with convex lenses, which are thicker in the middle than

Understanding OpticsUnderstanding OpticsUnderstanding OpticsUnderstanding OpticsUnderstanding Optics(cont)...(cont)...(cont)...(cont)...(cont)...


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4. Look at the diagrams below. Which is the eye of a farsighted person and which is the eye of a nearsighted person?

5. Imagine that you are an eye specialist. What type of lens would you prescribeto someone with the eye in diagram A?

6. What type of lens would you prescribe to someone with the eye in diagram B?

7. Write a paragraph describing how your life would be different if you had an eyedisorder and glasses and other visual aids had not yet been invented.

Diagram ADiagram ADiagram ADiagram ADiagram A

Diagram BDiagram BDiagram BDiagram BDiagram B


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Vocabulary ofVocabulary ofVocabulary ofVocabulary ofVocabulary ofUsing LightUsing LightUsing LightUsing LightUsing LightDirections: Unscramble the following vocabulary words and match eachword with its correct definition.

___ 1. ffradiction

___ 2. lucnetsnart

___ 3. nocceav

___ 4. zingiralop

___ 5. slen

___ 6. fracretion

___ 7. lectnoiref

___ 8. xvenoc

___ 9. dicinence

___ 10. paresnartnt

a. the process of light bouncing offobjects

b. material that allows most light topass through it

c. most plastics are an example of thistype of material

d. type of mirrors found in telescopesand car headlights

e. the bending of light as it passesthrough different mediums

f. the type of lens used inmagnifying glasses

g. the bending of light waves aroundthe edge of an object

h. the angle at which light strikes anobject

i. a transparent object that bends light

j. a type of filter that reduces glare

Using Light guide-double - Infobase

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