Reflection - shopgpn.comshopgpn.com/guides/711_0004g.pdfActivity One Š Front and Back _____ 11...

Teacher�s Guide

Reflection

Infrared

Table ofContents

Introduction _______________________________________ 3How to use the CD-ROM _______________________________ 4

Reflection ______________________________________Unit Overview and Bibliography _________________________ 7Background ___________________________________________ 8Video Segments ________________________________________ 9Multimedia Resources ___________________________________ 9Unit Assessment Answer Key ____________________________ 9Unit Assessment ______________________________________ 10Activity One � Front and Back _________________________ 11

Lesson Plan ______________________________________ 12Activity Sheet ____________________________________ 14

Activity Two � The Angle Tangle _______________________ 15Lesson Plan ______________________________________ 16Activity Sheet ____________________________________ 18

Activity Three � Throwing a Curve______________________ 19Lesson Plan ______________________________________ 20Activity Sheet ____________________________________ 22

InfraredUnit Overview and Bibliography ________________________ 23Background __________________________________________ 24Video Segments _______________________________________ 25Multimedia Resources __________________________________ 25Unit Assessment Answer Key ___________________________ 25Unit Assessment ______________________________________ 26Activity One � Focus on Radiation ______________________ 27

Lesson Plan ______________________________________ 28Activity Sheet ____________________________________ 30

Activity Two � Infrared Ray Gun _______________________ 31Lesson Plan ______________________________________ 32Activity Sheet ____________________________________ 34

Activity Three � As Clear As Glass ______________________ 35Lesson Plan ______________________________________ 36Activity Sheet ____________________________________ 38

Educational materials developed under a grant from the National Science Foundation — 3

IntroductionWelcome to the Newton’s AppleMultimedia Collection™!

The Newton�s Apple MultimediaCollection is designed to be used by ateacher guiding a class of students.Because the videos on the CD-ROMare intended to be integrated withyour instruction, you may find ithelpful to connect your computer toa projection system or a monitor thatis large enough to be viewed by theentire class. We have included avideotape of the segments so thatyou can use a VCR if it is moreconvenient. Although the CD-ROMwas designed for teachers, it can alsobe used by individuals or cooperativegroups.

With the help of many classroomscience teachers, the staff at Newton�sApple has developed a set of lessons,

activities, and assessments for eachvideo segment. The content andpedagogy conform with the Na-tional Science Education Standardsand most state and local curriculumframeworks. This Teacher�s Guidepresents lessons using an inquiry-based approach.

If you are an experienced teacher,you will find material that will helpyou expand your instructionalprogram. If you are new to inquiry-based instruction, you will findinformation that will help youdevelop successful instructionalstrategies, consistent with theNational Science Education Stan-dards. Whether you are new toinquiry-based instruction or havebeen using inquiry for years, thisguide will help your studentssucceed in science.

NaNaNaNaNational Science Educational Science Educational Science Educational Science Educational Science Education Standartion Standartion Standartion Standartion StandardsdsdsdsdsThe National Science Education Standards published by the NationalResearch Council in 1996 help us look at science education in a

new light. Students are no longer merely passive receivers of infor-mation recorded on a textbook page or handed down by a teacher.

The Standards call for students to become active participants in theirown learning process, with teachers working as facilitators and

coaches.

Our goal is to provide you with sound activities that will supplement

your curriculum and help you integrate technology into yourclassroom. The activities have been field tested by a cross section of

teachers from around the country. Some of the activities are morebasic; other activities are more challenging. We don’t expect that

every teacher will use every activity. You choose the ones youneed for your educational objectives.

Drawing from material shown onpublic television�s Emmy-award-winning science series, the multime-dia collection covers a wide varietyof topics in earth and space science,physical science, life science, andhealth. The Newton�s Apple Multime-dia Collection contains a CD-ROM,a printed Teacher�s Guide, a videowith two Newton�s Apple ®segments and a scientist profile, anda tutorial video.

The Teacher�s Guide provides threeinquiry-based activities for each ofthe topics, background informa-tion, assessments, and a bibliogra-phy of additional resources.

The CD-ROM holds a wealth ofinformation that you and yourstudents can use to enhance sciencelearning. Here�s what you�ll find onthe CD-ROM:

l two full video segments fromNewton�s Apple

l additional visual resources foreach of the Newton�s Apple topics

l background information oneach topic

l a video profile of a living scientistworking in a field related to theNewton�s Apple segments

l an Adobe Acrobat ® file contain-ing the entire teacher�s manualalong with student reproducibles

l UGather ® and UPresent ®software that allows you andyour students to create multime-dia presentations

l QuickTime ® 3.0, QuickTime ®3 Pro, and Adobe Acrobat®

Reader 3.0 installers in case youneed to update your currentsoftware

4 — Introduction

Teacher’sGuideWe suggest you take a few minutes tolook through this Teacher�s Guide tofamiliarize yourself with its features.

Each lesson follows the same format.The first page provides an overview ofthe activity, learning objectives, a list ofmaterials, and a glossary of importantterms. The next two pages present alesson plan in three parts: ENGAGE,EXPLORE, and EVALUATE.

l ENGAGE presents discussion questionsto get the students involved in thetopic. Video clips from the Newton�sApple segment are integrated into thissection of the lesson.

l EXPLORE gives you the information youneed to facilitate the student activity.

l EVALUATE provides questions for thestudents to think about following theactivity. Many of the activities in thecollection are open-ended and provideexcellent opportunities for perfor-mance assessment.

GUIDE ON THE SIDE and TRY THIS arefeatures that provide classroom manage-ment tips for the activity and extensionactivities.

Using the CD-ROMUsing the CD-ROMUsing the CD-ROMUsing the CD-ROMUsing the CD-ROMWhen you run the Newton’s Apple CD-ROM, you will find a main menu screenthat allows you to choose either of the twoNewton’s Apple topics or the scientistprofile. Simply click on one of the picturesto bring up the menu for that topic.

Once you have chosen your topic, use thenavigation buttons down the left side of thescreen to choose what information youwant to display.

The Background button brings up a shortessay that reviews the basic science con-cepts of the topic. This is the same essaythat is in the Teacher’s Guide.

Main Menu

Topic Menu


MultimediaToolsThe Newton�s Apple staff wants you to havea product that is flexible so that you canuse it in many different ways. All of thevideo clips used in the program are avail-able to you for display outside the pro-gram. You may combine them with otherresources to create your own multimediapresentations. You will find all the videoclips in folders on the CD-ROM. You arefree to use these clips in any way you likefor classroom use only. They cannot berepackaged and sold in any form withoutwritten permission of Newton�s Apple.

You will also find a folder for UGather®

and UPresent® . These two pieces ofsoftware were developed by the Universityof Minnesota. They allow you to createand store multimedia presentations. All ofthe information for installing and using thesoftware can be found in the folder. Thereis an Adobe Acrobat® file that allows youto read or print the entire user�s manual forthe software. We hope you will use thesevaluable tools to enhance your teaching.Students may also wish to use the softwareto create presentations or other projectsfor the class.

Video Menu

PlaPlaPlaPlaPlaying the Videoying the Videoying the Videoying the Videoying the VideoThe Video button allows you to chooseseveral different clips from the video segment.We have selected short video clips to comple-ment active classroom discussions andpromote independent thinking and inquiry.Each video begins with a short introduction tothe subject that asks several questions. Theseintroductory clips can spark discussion at thebeginning of the lesson. The Teacher’s Guidefor each activity presents specific strategiesthat will help you engage your studentsbefore showing the video. Each of the indi-vidual clips are used with the lesson plans forthe activities. The lesson plan identifies whichclip to play with each activity.

Once you select a video and it loads, you’llsee the first frame of the video segment. Thevideo must be started with the arrow at the leftend of the scroll bar. As you play the video,you can pause, reverse, or advance to anypart of the video with the scroll bar. You canreturn to the Clips Menu by clicking on theVideo button.

6 — Introduction

TechnicalInformationRefer to the notes on the CD-ROM casefor information concerning system require-ments. Directions for installing and run-ning the program are also provided there.

Make sure you have the most current ver-sions of QuickTime® and Adobe Acrobat®

Reader installed on your hard drive. Theinstallation programs for QuickTime 3,QuickTime Pro, and Acrobat Reader 3.0can be found on the CD-ROM. Double-click on the icons and follow the instruc-tions for installation. We recommend in-stalling these applications before runningthe Newton�s Apple Multimedia program.

TroubleShootingThere are several Read-Me files on the CD-ROM. The information found there coversmost of the problems that you might en-counter while using the program.

IntegraIntegraIntegraIntegraIntegratingtingtingtingtingMultimediaMultimediaMultimediaMultimediaMultimediaWe suggest that you have the CD-ROMloaded and the program running beforeclass. Select the video and allow it to load.The video usually loads within a couple ofseconds, but we recommend pre-loading itto save time.

All of the video segments are captioned inEnglish. The captions appear in a box at thebottom of the video window. You canchoose to play the clips in either English orSpanish by clicking one of the buttons at thebottom right of the screen. (You can chooseSpanish or English soundtracks for thescientist profile.)

The Resources button provides you withfour additional resources. There are addi-tional video clips, charts, graphs, slideshows, and graphics to help you teach thescience content of the unit.

The other navigation buttons on the left sideof the window allow you to go back to theMain Menu or to exit the program.

Resources Menu


ReflectionTeacher�s Guide

More Information

Here�s Lookingat Me

Themes and Conceptsl light and light wavesl reflectionl properties of reflective surfaces

National Science Education Content StandardsContent Standard A: Students should develop abilities necessary todo scientific inquiry.Content Standard B: Students should develop an understanding ofmotions and forces and transfer of energy.Content Standard G: Students should develop an understanding ofthe nature of science.

Activities1. Front and Back�approx. 15 min. prep; 45 min. class timeHow does the virtual image in a mirror relate in size to the realobject? How far is a virtual image from the real object? Using a flatmirror, a ruler, and a penny, students discover the relationshipbetween the virtual image in a mirror and the real object.

2. The Angle Tangle�approx. 20 min. prep; 45 min. class timeHow do individual light rays reflect off a mirror? Are there anyspecial laws that control the bounce of a beam of light off a shinysurface? Students discover the law of reflection using a flat mirror, aprotractor, and a light ray simulator,.

3. Throwing a Curve�approx. 20 min. prep; 45 min. class timeWhy do curved mirrors distort a reflection? Is there any way topredict how an image will change in a curved mirror? Students use alight ray simulator and a curved reflector to discover the relationshipbetween the bend in a mirror and the angle of reflection.

InternetNewton’s Applehttp://www.ktca.org/newtons(The official Newton’s Apple web sitewith information about the show and asearchable database of science ideasand activities.)

Laws of Reflection -Saskatchewan Education Dept.http://www.sasked.gov.sk.ca/docs/physics/u3b12phy.html(Good resource on the background ofthe laws of reflection. Includes teachingsuggestions, activities, and demonstra-tions.)

Diffuse Reflection Items -Hamburg Technical Universityhttp://uranus.mt2.tu-hamburg.de/~rb/Docs/povray/node122.html(Excellent overview on the subject ofthe diffuse reflection of light.)

Light and Optics -University of Oregonhttp://guernsey.uoregon.edu/~phdemo/demo/Light_and_Optics/LO-Optics.html(Good demonstrations on the reflectionof light and mirrors. Excellent diagramsincluded.)

What is a mirror? What is the difference betweenthe image you see in the mirror and the realobject? How does a mirror reflect light? What is thelaw of reflection and how does it apply to differenttypes of mirrors?

8 —Reflection

ReflectionInternet Search Wordsmirrorsopticsreflection of light

Books and ArticlesCassidy, J. Explorabook. Palo Alto, CA:Klutz Press, 1991.(A super source of fun activities usingmirrors and light waves.)

DiSpezio, M. Visual Foolery. Reading,MA: Planet Dexter (Addison-Wesley), 1995.(Many hands-on activities with mirrorsand optical illusions.)

Evans, H. (1996, May) “Ray TracingWith Hinged Mirrors,” The PhysicsTeacher. v34, n5.(Deals with the law of reflection.)

Gardner, R. Experiments With Light andMirrors. Springfield, NJ: EnslowPublishers, 1995.(A fine source of hands-on experimentsdealing with mirrors and the reflectionof light.)

National Council of Teachers ofMathematics, (1996, May) “Mirror,Mirror on the Wall,” Teaching ChildrenMathematics Magazine v2 n9.(A great lesson on the use of mirrors inplane geometry.)

Tomecek, S. Bouncing & Bending Light.New York: W.H. Freeman, 1995.(Reviews the basics of how mirrorswork, the law of reflection, the history ofmirrors, and common uses of mirrors)

Zubrowski, B. Mirrors: Finding OutAbout the Properties of Light. New York:Morrow Junior Books, 1992.(A good basic resource on mirrors andreflection.)

Community ResourcesScience museumsLocal college or university physicsdepartments

Mirror, mirror on the wall, why do you bother to reflect at all? Over theyears, mirrors have been thought of as bringers of both good luck andbad luck. They were often looked at as being the �window to the soul.�But the reflection you see in a mirror is merely the result of light wavesinteracting with a very smooth, shiny surface.

When light hits a surface, one of four things can happen: 1. It can passthrough the surface; 2. it can be absorbed, or soaked up, by the surface; 3.it can bend, or refract as it passes through a surface; 4) it can reflect, orbounce off of the surface back toward the observer. In fact, most peopledon�t realize it, but without reflection, you couldn�t see anything. Have youever been in a totally dark room with absolutely no light? Everything in theroom is invisible because there is no light to reflect back to your eye.

So if light is reflecting off everything you see, why can�t you see yourreflection in the page of a book or in the palm of your hand? It�s becausethese surfaces are rough. When light hits them, all of the rays bounce off indifferent directions and are scattered. Scientists call this type of reflection�diffuse reflection,� because the light bouncing off the surface is diffusedor spread out. In order for an object to reflect like a mirror, all of the lightrays that hit it have to bounce off at the exact same angle. To do this, thesurface has to be extremely smooth. This type of reflection is known asregular or specular reflection.

You may have noticed your reflection in a still pond or a puddle on a calmsunny day. That�s because the surface of the water is smooth. If the windstarts blowing, your image begins to break up because the little waves onthe surface make the water rough. In scientific terms, the light that wasreflecting in a specular manner became diffuse. When the water calmsdown again your image will reappear.

Water isn�t the only material that occasionally reflects light like a mirror.Smooth shiny metal, a clean plate, a freshly polished table top, and thescreen of your television set all make fairly good mirrors from time totime.

Whether it�s a mirror, a window, or the bumper on your friend�s car, allsmooth, polished surfaces reflect light according to the law of reflection.This rule is often stated that when a light ray strikes a mirror surface, theangle of incidence equals the angle of reflection. Simply put, whateverangle a ray of light hits a mirror, it will bounce off the mirror at the exactsame angle, but in the opposite direction.

So, the next time you pass a mirror, reflect for a moment on how it works!

Background


Video Segments

Multimedia Resources

Video & Stills

Introduction41:10 to 41:43�Newton�s host Dave Huddleston reflectsabout the images in mirrors. (33 sec.)

Video Clip 141:50 to 43:18�Movie actress Shelly Duvall observesthat the image in a mirror is the same distance fromthe front of the mirror as the real object. (1 min. 28 sec.)

Video Clip 344:12 to 44:58�Shelly Duvall discusses the law ofreflection and demonstrates how the angle of inci-dence always equals the angle of reflection for a rayof light. (46 sec.)

Video Clip 444:59 to 46:13�Shelly Duvall shows how a curvedmirror also follows the law of reflection, but becauseof the shape of its surface, the image produced iswarped. (1 min. 14 sec.)

Button AVideo: Newton�s Apple host Peggy Knapp demon-strates optical illusions with symmetry and mirrors.

Button BVideo: Newton�s Apple host Peggy Knapp usesbilliard balls and a pool table to demonstrate the lawof reflection.

Button CVideo: A simple animation from Newton�s Apple show-ing how light reflects off a curved surface.

Button DIllustration: Mirrors on the Hubble Space Telescope.

Unit Assessment Answer Key

Think about it1. The angle at which a ball hits a flat surface is the same

angle that the ball will bounce off the surface, providedthe ball is not spinning. The same is true for lightbouncing off a reflective surface.

2. The virtual image will appear to be the same distancefrom the surface of the mirror as the real object. Thesize�s of the virtual object and the real object are thesame.

3. The light rays leaving the surface of a concave mirrorwill converge. The light rays leaving the surface of aconvex mirror will spread apart. The light rays leavingthe surface of a flat mirror neither spread nor converge.

4. A mirror does not change the lettering in any way.The mirror merely obeys the laws of reflection,sending the images back to your eyes as they hit themirror. The image appears reversed, because youturn the image around to �show� it to the mirror.

5. A virtual image appears reversed to a person viewingit in a mirror. It appears reversed because you mustturn the original image around so it faces the mirror.A photo graphic image is not reversed.

What would you say?6. b 7. a 8. c 9. c 10. a

Video Clip 243:18 to 44:12�Shelly Duvall explains how the imagein a mirror appears to be reversed. (54 sec.)

The Unit Assessment on the following page covers the basic concepts presented in the Newton�s Apple videosegment and the background section in this guide. The assessment does not require completing all of theactivities. The Unit Assessment may be used as a pre- or post-test. However, students should view the completeNewton�s Apple video before doing this assessment. There is additional assessment at the end of each activity.

Unit Assessment

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10 — Reflection

What do you know aboutmirrors and reflection?

Answer these questions in your journal or on a separate sheet of paper.

Think about it1. In what way is light reflecting off a mirror

similar to a ball bouncing off a wall?

2. How is a virtual image in a flat mirror similarto the real object?

3. How is the reflection off a curved mirrordifferent than the reflection off a flat mirror?

4. What does a mirror do to make letters appearreversed?

5. How is a photographic image different from avirtual image in a mirror?

What would you say?6. If you look into a mirror and your face

appears to be stretched out, what�s probablywrong withthe mirror?a. The mirror is dirty.b. The mirror is curved.c. The mirror is cracked.d. The mirror is made out of plastic.

7. If you�re standing 5 feet in front of a mirror,how far should your reflection appear to bebehind the mirror?a. 5 feet.b. 10 feet.c. Your reflection should be in front of the mirror.d. 25 feet.

8. If you shine a flashlight directly into a mirrorat a 90 degree angle, which way will the beamof light be reflected?a. To the left.b. To the right.c. Straight back at the flashlight.d. It won t be reflected at all.

9. Which statement best describes the �law ofreflection�?a. The angle of incidence is less than the angle of reflection.b. The angle of incidence is greater than the angle of reflection.c. The angle of incidence equals the angle of reflection.d. Light can only reflect off of flat mirrors.

10. Which of the following statements is false? When you press your hand on a mirror � a. the image of your hand will be smaller than your hand. b. your hand appears opposite the way your

friend would see it if you were holding it up to them. c. the image of your hand will be the same

size as your hand. d. the image will appear smaller as you move our hand away from the surface of the mirror.


Activity 1

Important Terms

What is a virtual image? How does the size of a virtual image compare to the size ofthe object in front of the mirror? Are the real object and the virtual image the samedistance from the surface of the mirror?

Front and Back

OverviewStudents investigate the properties of mirrors and virtual images.Using a flat mirror, a ruler, and a penny, students discover therelationship between the virtual image in a mirror and the realobject.

ObjectivesAfter completing this activity, students will be able to�l compare the qualities of a real object and its virtual imagel explain how the distance to the virtual image in a mirror relates

to the real object it is reflecting.

Time NeededPreparation: approximately 15 minutesClassroom: approximately 45 minutes

MaterialsFor the teacher:l large, flat, rectangular mirror

For each group of students:l small, flat, rectangular mirrorl pennyl 30 cm ruler with mm gradationsl pencill plain sheet of 8.5" x 11" paper

Getting Readyreflection — The image of an objectthat you see in a mirror. Mirrors are ableto reflect images because mirrors reflectlight.

refract — To bend light. When lightpasses from one substance to an-other—such as from water to air orthrough a prism—it refracts or bends.

virtual image — The image that yousee in a mirror.

Here’s How

12 — Reflection

Reflection

Preparationl Set up the computer to play the CD-ROM (or set up the VCR

and cue the tape).l Gather the materials for each team of students.l Make a copy of Activity Sheet 1 for each student.l Review the information in the Background on page 8.

Video Clip 141:50 to 43:18

Movie actress Shelly Duvall observesthat the image in a mirror is the same

distance from the surface of the mirroras the real object. (1 min. 28 sec.)


Shelly Duvall explains how a mirrorappears to reverse an image. (54 sec.)

Engage (Approx. 15 minutes)Hold up a large mirror and ask students to describe some of the character-istics of reflections in the mirror. Have them pay particular attention to thesize, shape, and color of the reflections compared to the objects makingthem. Ask students for similarities and differences between the image andthe real object. Accept all responses.

Show Video Clip 1 [41:50 to 43:18] in which Shelly Duvall observesthat the image in a mirror�the virtual image�appears the samedistance from the surface of the mirror as the real object. Ask thestudents to think of how they could check if this is true. Accept allsuggestions. Ask them how Shelly Duvall proves it to herself.

Ask students if they have ever tried to read anything in a mirror. Ask themwhat happens to letters of the alphabet. Show Video Clip 2 [43:18 to44:12]. Discuss Shelly�s explanation about the reversal of an image in amirror.

Explore (Approx. 30 minutes)Tell students that they will work in groups to measure the distance tothe virtual image in a mirror. By using an object to sight on thevirtual image, they will be able to estimate how far behind the mirrorthe virtual image appears to be.

Have the students work together in small groups. Begin by folding ablank sheet of paper in half so that there are two equal sections8.5" x 5.5" in size. Tell students to draw a line across the paper at thefold and hold the paper so that the line in the fold crosses from left toright. Using the metric ruler, have the students measure and drawlines at 2-cm increments from the center line to the end of the sheet ofpaper. The lines will be at 2, 4, 6, 8, 10, and 12 cm.

l You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [41:10 to41:49]. Find out what studentsalready know about reflection. As aclass, discuss the questions posed byDave Huddleston.

l Remind students to hold the mirrorperpendicular to the paper. Ask themto think of what might happen to theirresults if they were to tilt the mirrorforward or backward.

l Judging the distance of an objectbehind the mirror is a bit tricky. Askstudents to think of some way thatmight help them make their measure-ment.

l All the measurements are done ona horizontal plane. Could studentsconduct the experiment with themirror lying flat on the table andholding the penny above it? Whatwould be some of the drawbacksassociated with doing the experimentin this fashion? Have them try it andcompare the results to the first set ofdata.

l If it is appropriate, view the entireNewton’s Apple video segment onreflection after completing the activity.

Guide on the Side


Try This

Activity 1

With the paper lying flat on a table, have the students place the mirroron the center line so that the mirror is perpendicular to the paper andtable. Students will see a �virtual scale� in the mirror. Tell students toleave a 4-cm margin along the right edge of the paper so that they cansee the edge of the paper as it extends behind the mirror.

Tell students to place the penny at the 4-cm mark in front of themirror. Have them lay a pencil flat on the right edge of the paper sothat it is in line with the mirror. Next, using their depth perception toguide them, students slowly roll the pencil back along the right-handside of the paper and stop when they feel that the pencil is in directline with the virtual image �behind� the mirror. Students mark thispoint on the paper and use a ruler to measure the distance from thecenter line. Tell students to record the measurement in their journalsand then repeat the activity with the penny at the 8- and 12-cm marks.

Evaluate1. What happens to the size of the virtual penny as you move the realpenny further away from the mirror. (The virtual penny gets smaller.)

2. How does the distance measured to the virtual penny compare with thedistance that the real object is in front of the mirror? (The two distances areequal.)

3. If you placed the penny head-side-up, which direction would AbrahamLincoln be facing? (The virtual image would be facing left.)

Construct mirrors using aluminum foil,plastic plates, or other shiny surfaces.Do these mirrors follow the same rulesfor a virtual image as a real mirror? Howare they different?

Try to produce multiple reflections byusing two mirros. Experiment with themirrors to create different effects, suchas the appearance that the reflectionsgo on forever. Figure out how thevirtual image rule applies to yourdiscovery. Share your experiment andobservations with the class.

Architects and designers have usedmirrors to change the appearances of aroom. For example, mirrored walls areoften used to make a small room looklarger. Investigate the use of mirrors inbuildings to learn other applications ofmirrors in architecture. Report yourfindings to the class.

14 — Reflection

NameNameNameNameName ______________________________________ Class Period______________________________________ Class Period______________________________________ Class Period______________________________________ Class Period______________________________________ Class Period _______________________________________________________Activity Sheet 1

Copyright © Twin Cities Public Television & GPN. Permission granted to reproduce for classroom use.

FrFrFrFrFront and Backont and Backont and Backont and Backont and BackWhaWhaWhaWhaWhat you�re going to dot you�re going to dot you�re going to dot you�re going to dot you�re going to doYou re going to investigate how the depth of a virtual image in a mirror relates to the distance of the realobject from the surface of the mirror.

HoHoHoHoHow to do itw to do itw to do itw to do itw to do it1.1.1.1.1. Work with your group. Begin by folding ablank sheet of paper in half. Next, draw a lineacross the paper at the fold. Using a metricruler, measure and draw lines at 2-cm incre-ments from the center line to the end of thesheet of paper. The lines will be at 2, 4, 6, 8,10, and 12 cm.

2.2.2.2.2. Place the sheet of paperon a level surface like a table.Hold the mirroron the center lineof the paper so thatthe mirror is perpen-dicular to the paper andtable. Leave a 4-cm margin along the rightedge of the paper so that you can see the edgeof the paper as it extends behind the mirror.You will be able to see the �virtual scale� inthe mirror.

3.3.3.3.3. Put a penny at the 4-cm mark in front ofthe mirror. Lay the pencil flat on the paper sothat it is in line with the mirror. Then, slowlyroll the pencil back along the right hand sideof the paper and stop when you think that thepencil is in direct line with the virtual imageof the penny behind the mirror. Mark thispoint on the paper. Measure the distance fromthe center line to the point marking the loca-tion of the virtual image. Record the measure-ment in your journal. Repeat the activity withthe penny at the 8- and 12-cm marks.

RecorRecorRecorRecorRecording your dading your dading your dading your dading your datatatatataSet up a data table in your journal to record yourmeasurements and other observations. The datatable should include the following kinds ofinformation for each trial.

Distance of the penny from the front of the mirror

Estimated distance (distance of pencil mark) ofvirtual image behind mirror

Observed distance of the virtual image behindthe mirror

Other observations

WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?How does the distance of a penny in front of amirror compare to the depth of its virtualimage in the mirror?

How accurate were your estimations? Wasthere a difference in accuracy as the distance ofthe penny from the mirror increased? Whatmight account for the difference between theestimate and the observed distance?

Repeat the experiment using other objects ofdifferent sizes. Does each of them produce thesame relationship?


Activity 2

Important Terms

The Angle TangleHow does light reflect off a mirror? What is the law of reflection? What happens tolight that strikes a mirror at a 90-degree angle?

OverviewStudents learn how the law of reflection works. Using a simple lightray device, a protractor, and a flat mirror, students make observationsand take measurements to test the law of reflection.

ObjectivesAfter completing this activity, students will be able to�l explain the law of reflection as it applies to mirrorsl measure the angles of incidence and reflection for lightl predict the angle of reflection for a beam of light striking the

surface of a flat mirror

Time NeededPreparation: approximately 20 minutesClassroom: approximately 45 minutes

MaterialsFor the teacher:l smooth, flat walll handball or similar bouncy balll metric ruler

For each group of students:l flashlightl protractorl combl 6 inches of duct tape or electrical tapel pencill small, flat, rectangular mirrorl copy of the template

Getting Readyangle of incidence — The angle atwhich a ray of light strikes the surface ofa mirror.

angle of reflection — The angle atwhich a ray of light bounces off thesurface of a mirror.

symmetry — A balanced arrangementof parts on either side of a line or centerpoint.

16 — Reflection

ReflectionHere’s How


and cue the tape).l Prepare and copy the template for the student activity.l Gather the materials for each team of students.l Make a copy of Activity Sheet 2 for each student.l Review the information in the Background on page 8.


Movie actress Shelly Duvall explainsthe law of reflection and demonstrates

how, for a ray of light, the angle ofincidence always equals the angle of

reflection. (46 sec.)

Engage (Approx. 15 minutes)Ask students how many of them have played tennis or handball. Ask themhow they would bounce a ball off a wall if they wanted it to come straightback at them. (You would have to throw it straight so that it hit the wall ata 90-degree angle.) Ask what would happen if you threw the ball at thewall at a smaller angle. (The ball would bounce off in the oppositedirection at the same angle.)

Demonstrate angular rebound by throwing a ball against a wall at severaldifferent angles. (You may wish to perform this demonstration in a gym oroutside.) Have two students stand 4 to 5 meters apart, a meter or twofrom the wall. Hand one of them the ball. Tell them they are to bounce theball off the wall so that it goes to their partner. Ask how they decide whatangle to throw the ball for it to bounce to the partner. Explain thatthe way a ball bounces off a wall is very similar to the way lightbounces off a mirror. Explain that they are going to do an activitythat will test this idea.

Explore (Approximately 30 minutes)For this activity, you will need to enlarge the miniature templateshown on Activity Sheet 2. The template should be large enough tofill a 8.5� x 11� sheet of paper. The �Place mirror here� line shouldrun all the way across the top of the sheet. The �Normal line� isperpendicular to the mirror line and should be centered on the sheet.Lines A, B, C, and D should form angles of approximately 70°, 45°,20°, and 5° to the mirror line. Make copies of the full-sized templatefor each group.

Separate students into groups and explain that they are going to use aprotractor to measure the incident and reflected light from a speciallyadapted flashlight.

l You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [41:10 to41:49]. Find out what studentsalready know about reflections. As aclass, discuss the questions posed byDave Huddleston.l During the Engage portion of thelesson, you may wish to show thevideo clip found at Resource Button B.This clip shows the angles of inci-dence and reflection using a billiardtable.l Before starting the activity, youmay wish to review how to measureangles using a protractor.l To have the activity work mosteffectively, make the room as dark aspossible.l Ask the students to think abouthow the results might change if themirror were not placed directly on topof the line. Would the angle readingsbe accurate? Why or why not?l Once the students have traced andmeasured a few light rays, have themtry the opposite. Have them draw aline to the mirror representing incidentlight and then predict where thereflected ray will go. Use the flashlightto check the predictions.l If it is appropriate, view the entireNewton’s Apple video segment onReflection after completing the activity.

Guide on the Side


Activity 2Try This

Have the groups assemble the light ray device by placing a comb overthe front of a flashlight lens so that light shines through the teeth.Using the electrical tape, have students cover all the spaces except forone in the middle. This light should project a single light ray acrossthe table when the flashlight is lying flat.

Have students place the template on a desktop. Have one member ofthe group hold the mirror straight up and down along the line thatsays �Place mirror here.� The black line that says �Normal Line�should look like it�s going straight through the mirror. If it appearsbent where it strikes the mirror, students should adjust the mirror sothat the line is straight.

Have students in each group turn on the flashlight and lay it flat on thetable. Place it so that the comb is parallel with the line marked �A� on theactivity sheet. With a pencil, have them trace the light ray as it strikes themirror and bounces off. Label this line �A,� and repeat the procedure forspots �B,� �C,� and �D.� Students should trace down the center of thelight ray.

After students have traced all four light rays, they should remove the mirrorand use the protractor to measure the angle that each line makes with themirror line. Have them measure the incident ray and reflected ray sepa-rately and record the angles on the data sheet. If time permits, havestudents try several additional ray angles of their own.

Ask students what they discovered. Conclude by showing Video Clip 3[44:12 to 44:58] in which Shelly Duvall explains the law of reflectionand demonstrates that the angle of incidence of light always equals theangle of reflection. An additional video clip demonstrating thisprinciple can be found at Resource Button B.

Evaluate1. How do your measurements for the incident and reflected rays comparewith each other? What are some of the sources of error that might beskewing the results? (The two measurements should be about equal. Errorsusually result from the mirrors not being exactly parallel to the line or fromincorrectly traced lines.)

2. What would happen to a light ray that was directed into the mirror froma line perpendicular to the mirror? (It would come directly back intothe flashlight.)

3. How does changing the distance from the flashlight to the mirroraffect the way the light is reflected? (It should have no effect on theangle; however, the light ray becomes wider as the distance is in-creased.)

Periscopes are devices that use twomirrors set at angles parallel to eachother so that a person can see anobject around a corner or from belowthe surface of water. Construct aperiscope of your own using two smallmirrors and a quart-size paper milkcontainer. The directions can be foundin many books.

You may have noticed the word“ambulance” written in reverse on thefront of emergency vehicles. This is sothe words appear correct when viewedthrough the rearview mirror of the car.Mirror writing can be confusing, but italso can be fun. Try writing your nameso that it appears correct when viewedin a mirror. How does the law ofreflection control the way the letters areprinted?

View the video clip found underResource Button A on the CD-ROM.Think of other ways mirrors could beused to set up optical illusions. Try outsome of your ideas and demonstratethem to the class.

In art, symmetry involves repeatedpatterns of similar design. Kaleido-scopes are devices that use mirrors setat specific angles to produce symmetri-cal images. Investigate how kaleido-scopes are made and then try makingyour own kaleidoscopic images.Experiment with changing the size ofthe angle between the mirrors and thenumber of mirrors used.

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Name ______________________________________ ______________________________________ ______________________________________ ______________________________________ ______________________________________ Class Period _______________________________________________________Activity Sheet 2

Angle TAngle TAngle TAngle TAngle TangleangleangleangleangleWhaWhaWhaWhaWhat you�re going to dot you�re going to dot you�re going to dot you�re going to dot you�re going to doYou re going to build a light ray device and use it to explore the law of reflection.

HoHoHoHoHow to do itw to do itw to do itw to do itw to do it1.1.1.1.1. Work withyour group andassemble thelight ray device byplacing a comb over thefront of a flashlight lens sothat light shines through theteeth. Using the electrical tape,cover all the spaces except forone in the middle.

2.2.2.2.2. Place the template on a level surface suchas a tabletop. Have one member of your grouphold the mirror straight up and down alongthe line that says �place mirror here� on thetemplate. The �Normal Line� should look likeit s going straight through the mirror. If itappears bent where it strikes the mirror,adjust the mirror so that the line is straight.

3.3.3.3.3. Turn on the flashlight and lay it flat onthe table. Place it so that the comb is parallelwith the line marked �A� on the activitysheet. With a pencil, trace the light ray as itstrikes the mirror and bounces off. Label thisline �A,� and repeat the procedure for �B,��C,� and �D.�

4.4.4.4.4. After you have traced the lines, removethe mirror and use the protractor to measurethe angle that each line makes with the mirrorline. Measure the incident ray and reflectedray separately and record the angles on thedata sheet.

RecorRecorRecorRecorRecording your dading your dading your dading your dading your datatatatataSet up a data table in your journal to recordyour measurements and other observations.The data table should include the followingkinds of information for each position for thetest:

Position ______

Angle of incident light _______

Angle of reflected light _______

Other observations:

WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?The law of reflection states that the angle ofreflected light is equal to the angle of incidentlight. Did your group find this to be true?Explain.

Compare your results with other groups�results. What might have caused any differ-ences in your results?


Activity 3

Important Terms

Throwing a CurveWhy does a curved mirror make your face look funny? Do curved mirrors reflectlight the same way that flat mirrors do? Does the law of reflection apply to curvedmirrors too? Do curved mirrors have any practical uses?

OverviewStudents discover how a curved mirror not only changes the reflectionof an image, but follows the same law of reflection as a flat mirror.

ObjectivesAfter completing this activity students will be able to �l explain how a curved mirror reflects lightl demonstrate how the law of reflection works with a curved

mirror

Time NeededPreparation: 20 minutesClassroom: 45 minutes

MaterialsFor the teacher:l large, flexible plastic mirror at least 30 cm squarel metric ruler

For each group of students:l flashlightl pocket combl small, flexible plastic rectangular mirrorl small, flat, rectangular mirrorl pencill metric rulerl protractorl copy of the template

Getting Readyconcave — A surface that is curvedinward.

convex — A surface that is curvedoutward.

focal length — The distance to the focalpoint

focal point — The point at which anumber of light rays converge afterpassing through a lens or reflecting offa mirror.

20 — Reflection

ReflectionHere’s How


and cue the tape).l Prepare and copy the template for the activity.l Gather the materials for each team of students.l Make a copy of Activity Sheet 3 for each student.l Review the information in the Background on page 8.


Actress Shelly Duvall shows how acurved mirror also follows the law of

reflection, but because of the shape ofits surface, the image produced is

warped. (1 min. 14 sec.)

Engage (Approx. 15 min.)Hold up a large, rectangular, plastic mirror and move among the studentsso that they can see their reflections. As they are looking, gently bend in thetwo sides of the mirror so that the mirror is curved. Ask students whatthey observed. Ask the students if they think the law of reflection appliesto both curved mirrors and flat mirrors. Accept all answers.

View Video Clip 4 (44:59 to 46:13) in which Shelly Duvall shows howthe law of reflection applies to a curved mirror. Ask if anyone canexplain why Shelly appears upside down in the spoon. Review howthe curved reflector obeys the same law of reflection as a flat mirror.Ask students if they can think of any situations where a curved mirrormight be better than a flat mirror. (In stores and in elevators. Also,the side-view mirrors of cars are curved.) Explain to students that theyare going to use light rays and curved reflectors to explore the law ofreflection and its application to curved mirrors.

Explore (Approx. 30 min.)Prepare and photocopy this template for students. On an 8.5� x 11� sheetof paper, draw a line the length of the paper about 3 cm from the leftedge. Label the line �Place the mirror here.� Next, about 10 cm from themirror line draw a 3-cm line at an angle of about 20° to the mirrorline. Label the line �A.�

Have students work with classmates in small groups. Demonstrate how toset up the light ray simulator by taping a comb onto the lens of aflashlight (see Explore, Activity Two). Tell students that each team isgoing to observe how light rays behave as they bounce off threedifferent surfaces: a convex reflector, a flat reflector, and a concavereflector. Using a pencil, they will trace the light ray patterns anddraw some conclusions about the law of reflection.

Guide on the Sidel You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [41:10 to41:49]. Find out what studentsalready know about reflection. As aclass, discuss the questions posed byDave Huddleston.

l The diagram found at ResourceButton C provides a useful illustrationof how light reflects off a curvedsurface.

l Before beginning the exploresection, be sure students understandthe terms concave and convex.

l In the 1400s, Leonardo da Vincideveloped a new type of art called“anamorphic art”. In this art form, acurved mirror is used to change adistorted image into a clear image.Have students use the informationthey have discovered in this activityabout how curved surfaces reflectlight to make an anamorphic drawingthat becomes a clear virtual image.

l Flexible mirrors used for campingand backpacking work well for thisactivity.

l If it is appropriate, you may wish toview the entire Newton’s Apple videosegment on reflection after completingthe activity.


Activity 3Try This

Have students place the template on a desktop. Have them place theflashlight and comb on the sheet at line �A.� Students place the mirror onits edge on the mirror line and have one group member hold it steady.Students have another member of the group trace the incident and re-flected light ray on the activity sheet. This set of rays will be the �standard�to which the other rays will be compared. Students repeat the procedureholding a convex mirror on the mirror line. Have students make surethat they hold the mirror steady on its edge so that the reflected raysare projected onto the paper. Have students repeat the same steps withthe concave side of the mirror.

Next, have students use the protractor to measure the angles on thethree sets of ray patterns. If time permits have the students experi-ment with distances from the flashlight to the different reflectors.Sliding the reflector back an forth, they should note any changes inthe ray patterns.

Evaluate1. What did you observe about the light ray pattern from the convexreflector compared to the light reflected from the flat mirror? (The lightrays from the convex mirror spread out more.)

2. What happened to the ray patterns for the three reflectors as youchanged the distance between the light and the surface of the reflector?(The flat mirror stayed the same, the convex reflector spread outmore, and the concave reflector brought all the rays together.)

3. Based on this activity, what can you conclude about the law of reflectionand curved mirrors? (The angle of incidence still equals the angle ofreflection; however, these angles are determined by how much the surfaceof the mirror is curved.)

Curved mirrors can be used to spreadlight rays out or to concentrate them intoa single focal point. In the 1700s, IsaacNewton developed a telescope usingconcave mirrors instead of lenses tomagnify images of stars and planets.Today, some of the most powerfultelescopes (including Hubbell) use thistechnology to see farther into spacethan ever before. Investigate thedevelopment of reflecting telescopesand see how they have changed overthe years. What are some of the biggestscopes and what new “active optics”are being used in the future?

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22 — Reflection Copyright © Twin Cities Public Television & GPN. Permission granted to reproduce for classroom use.

NameNameNameNameName ______________________________________ Cl______________________________________ Cl______________________________________ Cl______________________________________ Cl______________________________________ ClassPeriodassPeriodassPeriodassPeriodassPeriod _______________________________________________________Activity Sheet 3

TTTTThrhrhrhrhrooooowing a Curwing a Curwing a Curwing a Curwing a CurveveveveveWhaWhaWhaWhaWhat you�re going to dot you�re going to dot you�re going to dot you�re going to dot you�re going to doYou re going to compare how light rays reflect off both curved and flat mirrors. You will test a concavereflector, a convex reflector, and a flat mirror, and measure the angle of incidence and reflection for each.

HoHoHoHoHow to do itw to do itw to do itw to do itw to do it1.1.1.1.1. Work with your group. Your teacherwill explain how to make a light raysimulator from a flashlight.

2.2.2.2.2. On a sheet of paper, place the lightray simulator 10 cm from a flat rectangu-lar mirror. Have a classmate trace theincident and reflected light rays. This setof rays will be the standard to which theother rays will be compared. Repeat theprocedure using a convex mirror. Fol-low the same with concave mirror.

3.3.3.3.3. Next, use a protractor to measurethe angles on the three sets of ray pat-terns. If time permits, experiment withdistances from the flashlight to thereflectors, and note any changes in thelight ray patterns.

RecorRecorRecorRecorRecording your dading your dading your dading your dading your datatatatataSet up a data table in your journal torecord your measurements and otherobservations. The data table shouldinclude the following kinds of informa-tion for each of the reflector types youare using for the test.

Type of reflector ______

Position ______

Angle of incident light _______

Angle of reflected light _______

Other observations:

WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?How do the angles of incident and reflected light from a flat surfacecompare with those from a curved surface?

What patterns did you observe? Do these patterns follow the law ofreflection? Explain.


InfraredTeacher�s Guide

More Information

Infrared RadiationWhat is infrared? Is infrared light the same asinfrared radiation? Is infrared radiation dangerous?Is infrared radiation red? Why can’t we see infraredradiation? What can you use infrared radiation for?How do you know infrared radiation exists if it isinvisible?

Themes and Conceptsl electromagnetic radiationl electromagnetic spectruml wavelength and frequencyl visible lightl infrared radiationl heat

National Science Education StandardsContent Standard A: Students should develop abilities necessary to doscientific inquiry.Content Standard B: Students should develop an understanding of thetransfer of energy.Content Standard G: Students should develop an understanding of thenature of science.

Activities1. Focus That Radiation�Approx. 20 min. prep; 45 min. class timeHow do we know infrared radiation exists if we cannot see it? Stu-dents measure the heat generated by infrared radiation that is focusedthrough a lens.

2. Infrared Ray Gun�Approx. 20 min. prep; 50 min. class timeHow is infrared radiation similar to visible light? How is it different?Students use a TV remote control unit to explore and compare the proper-ties of infrared and visible light.

3. As Clear as Glass�Approx. 10 min. prep; 70 min. class timeWhy does the interior of a car get superheated in the sunlight? Why is italways warm inside a greenhouse? Students explore how infrared radiationpasses (or doesn�t pass) through glass.

InternetNewton’s Applehttp://www.ktca.org/newtons(The official Newton’s Apple web sitewith information about the show and asearchable database of science ideasand activities.)

Infrared Astronomy—NASAhttp://www.ipac.caltech.edu/Outreach/Edu/outreach.html(A complete site on the subject ofinfrared.)

ACEPT, Patterns in Nature—Arizona State Universityhttp://acept.la.asu.edu/PiN/mod/light/colorspectrum/pattLight30bj3.html(Learn about infrared and how it’sused.)

Electromagnetic Spectrum—NASAhttp://observe.ivv.nasa.gov/nasa/education/reference/reflect/ir.html(A good site on understanding thestructure of the electromagneticspectrum.)

Internet Search Wordsinfraredinfrared astronomyinfrared satelliteselectromagnetic spectrum

24 — Infrared

BooksFord, Brian J. First Encyclopedia ofScience. New York: Random House,1993.(A good discussion of the relationshipbetween infrared radiation and heat.)

Lafferty, Peter. Heat and Cold. New York:Benchmark Books, Marshall CavendishCorporation, 1996.(Contains a good infrared scan of ahuman brain and a nice description ofinfrared radiation.)

The Exploratorium Science Snackbook.San Francisco: The Exploratorium,1991.(Contains a few good descriptions ofinfrared experiments and museumexhibits.)

White, Laurie. Infrared PhotographyHandbook. Amherst, NY: AmherstMedia, 1996,(A practical guide to using Infrared filmin your camera. Contains a number ofinfrared photographs.)

Wood, Robert W. Physics for Kids—49Easy Experiments with Heat. Blue RidgeSummit, PA: Tab Books Inc., 1990.(Contains a variety of simple experi-ments that can be done with householditems.)

BackgroundInfrared radiation carries information from a remote control to a TV,helps us see in the dark, and keeps food warm in restaurants. What isit? In the late 1600s, Isaac Newton discovered that white light was amixture of colors on a spectrum. It was the first step in understandingthe electromagnetic spectrum, the very broad band of radiation thataccounts for much of what we experience in the universe around us.

Visible light, the part of the spectrum that humans can see with thenaked eye, is only one type of radiation. It makes up only a very smallpart of the broad electromagnetic spectrum. Our eyes aren�t sensitiveto the other parts of the electromagnetic spectrum, but the entirespectrum is still there. Starting with the shortest, high-frequencywaves, and moving to the longest, low-frequency waves, the electro-magnetic spectrum consists of: Gamma rays, X-rays, ultraviolet light,visible light, infrared radiation, microwaves, and, finally, radio waves.Although we can�t see much of this radiation, there are instrumentswe can use to make it visible.

Infrared radiation is an important form of radiation that is used byeveryone from astronomers to police. Infrared radiation is connectedto heat in a very special way. As an object gets warmer, its atomsvibrate with increasing speed. A rapidly vibrating atom emits infraredradiation waves like a wiggling tadpole creates waves in a pond. Whensomething is struck by infrared radiation, the object�s atoms start tovibrate faster and faster. The object gets warmer. Increase the expo-sure, and it goes from warm to hot.

As atoms vibrate faster and faster, the frequency of the electromag-netic waves increases and the radiation moves up the spectrum fromthe infrared region into visible light. You can see this phenomenon ina toaster. As electricity flows through the heating coils, the atoms inthe coils begin to vibrate. As they heat up, they emit infrared radia-tion. The heat grows and the vibration rate increases. Soon the �fre-quency� of the radiation is in the range of visible light, and the coilsappear to glow red.

Infrared radiation was discovered around 1800 by British astronomerWilliam Herschel. He found infrared radiation with a thermometerand a prism, but today infrared cameras are used. Warm objectsappear brighter than cooler objects when seen through an infraredcamera.

Infrared cameras are used extensively in police helicopters to searchfor missing persons. Similar cameras permit nighttime navigation andenemy location in military combat vehicles. Weather satellites usesuch cameras to better monitor changing weather patterns and theHubble Space Telescope can study newly formed stars through aspecial infrared camera.

The more you learn about infrared radiation, the more you begin torealize that science covers a whole spectrum of ideas!

Infrared


Video & Stills

Video Segments

Additional Resources

Introduction46:28 to 47:11�Newton�s Apple host Eileen Galindo posessome interesting questions about infrared radiation. (43 sec.)

Video Clip 147:14 to 49:02�David Heil and Dr. Paul Kruse takea look at infrared radiation. (1 min. 12 sec.)

Video Clip 350:08 to 51:04�Maj. Matt Ferrin shows film ofmoving vehicles taken through an infrared �thermalsight� on a tank. (56 sec.)

Video Clip 449:02 to 50:03�David Heil and Paul Kruse discussinfrared radiation, visible light, and the electromag-netic spectrum. (1 min. 1 sec.)

Button ADiagram: A chart showing the electromagnetic spectrum.

Button BPicture: Satellite photos of San Antonio, TX, taken by aninfrared camera.

Button CPicture: Infrared photo of a person holding a lit match.

Button DVideo: Infrared image of David Heil�s face.

Unit Assessment Answer KeyThe Unit Assessment on the following page covers the basic concepts presented in the Newton�s Apple video segmentand the Background section in this guide. The assessment does not require completing all of the activities. TheUnit Assessment may be used as a pre- or post-test. However, students should view the complete Newton�sApple video before doing this assessment. There is additional assessment at the end of each activity.

Think about it1. View the person with the camera; if someone had

a fever, his or her face would glow brighterthan other people�s faces because it would bewarmer.

2. Clothing that covers your entire body�headand hands included�and insulates well wouldmake you less visible to an infrared camera.

3. Answers will vary, but should deal with theinfrared camera�s sensitivity to heat radiationrather than to light. Sample answer: An exterminator could use it to find a mouse nest inside awall.

4. All cold-blooded animals are dependent oninfrared radiation for survival; they must warmthemselves in the sun to become active.

5. A hot sidewalk would be glowing brightly and thecool grass would look dark.

What would you say?6. c 7. a 8. b 9. d 10. c

Video Clip 251:04 to 53:17�David Heil and Paul Kruse discusspractical applications of infrared radiation.(2 min. 13 sec.)

26 — Infrared

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Unit Assessment

What do you know aboutInfrared Radiation?

Write the answers to these questions in your journal or on a separate sheet ofpaper.

Think about it1. How could you tell if someone had a fever by

using an infrared camera?

2. How would you make yourself look invisible toan infrared camera?

3. Can you think of any new uses for an infraredcameras?

4. What kind of animals depend on infraredradiation for survival?

5. What would a sidewalk and a nearbylawn look like through an infrared camera on a sunny day?

What would you say?6. The gray filament of an oven that is heating

up would appear�a. dark gray to an infrared camera.b. red to an infrared camera.c. nearly white to an infrared camera.d. invisible to an infrared camera.

7. As the temperature of an object increases, thefrequency of the infrared radiation it emits�a. increases.b. decreases.c. stays the same.d. decreases then increases.

8. A person hidden in smoke can be seen by aninfrared camera unless�a. it is a hot, summer day.b. the smoke is at the same temperature as the person�s body.c. the camera is pointed directly at the smoke.d. bright light is shining on the smoke.

9. A light bulb produces more infrared radiationthan�a. a toaster.b. an oven.c. a theater spotlight.d. a fluorescent light.

10.Ultraviolet radiation is probably located onthe electromagnetic spectrum�a. between infrared radiation and visible light.b. next to infrared radiation, on the other side from visible light.c. above visible light, next to the violet end of the visible spectrum.d. all the way at one end.


Important Terms

Activity 1

Focus on RadiationIf you can’t see infrared radiation, how can it be measured? How is infraredradiation like visible light? How is it different? Is there an easy way to detect infraredradiation?

Getting ReadyOverviewStudents find the focal distance for a small lens and then focusinfrared radiation through the lens onto a thermometer. Studentsmeasure how removing the lens and moving it back changes thetemperature.

ObjectivesAfter completing this activity, students will be able to�l discuss the relationship between visible light and electromagnetic

radiation.l describe the relationship between electromagnetic radiation and

heatl demonstrate how infrared radiation can be detected and measured

Time NeededPreparation: Approximately 20 minutesClassroom: Approximately 45 minutes

MaterialsFor the teacher:l slide projectorl large prisml diagram of the electromagnetic spectrum

For each group of students:l 3 ring stands with clampsl common 16d iron naill 5 cm focal length lensl thermometerl modeling clay to hold the thermometer in the clampl Bunsen burner

electromagnetic spectrum — Theentire known range of electromagneticradiation.

frequency — The number of times anelectromagnetic wave oscillates eachsecond. The frequency of a light wavedetermines its color.

infrared radiation — The portion of theelectromagnetic spectrum with afrequency less than that of visible lightand greater than that of radio waves.

Here’s How

28 — Infrared

Infrared


and cue the tape).l Gather the necessary materials for the student experiments.l Set up the slide projector and prism.l Make copies of Activity Sheet 1 for each student.l Review the information in the Background on page 24.

Guide on the Side

Video Clip 147:14 to 49:02 David Heil and Dr. PaulKruse take a look at infrared radiation.

(1 min. 12 sec.)

l You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [46:28 to47:11]. Find out what studentsalready know about infrared radiation.As a class, discuss the questionsposed by Eileen Galindo.l Caution students to follow estab-lished classroom safety procedureswhen working with the Bunsen burnerand red-hot nail.l Lenses with a 5 cm focal lengthcan be obtained from most scienceequipment supply companies.l It helps to blacken the silver bulbof the thermometer with a washablemarker. This will allow it to absorbmore infrared radiation.l Heat sensitive strips made fromthermochromic liquid crystal mayreplace thermometers in this activity.They may be obtained from theExploratorium store in the form ofpostcards or from Edmonds Scientific.You should purchase strips that turnred at 80°F.l Students may wish to set up othervariables to test the flow of infraredradiation, such as blocking the lenswith a sheet of paper.l If time allows, you may wish tohave students view the entireNewton’s Apple video segment oninfrared radiation after completing thisactivity.

Engage (Approx. 15 minutes)Before class, set up the slide projector and prism. Place the prismabout a foot in front of the projector so that the light passes throughit and forms a bright spectrum on a nearby wall. Begin class bydimming the lights and having students observe the spectrum. Askstudents where the colors come from. (They are part of the whitelight.) Where in nature do we see these colors? (a rainbow) Explainthat the colors in the spectrum make up all of the electromagneticradiation that the human eye can sense. Lead the students to a discus-sion about the portion of the electromagnetic spectrum that isn�tvisible to the human eye. Find out if they are familiar with otherforms of electromagnetic radiation: radio waves, microwaves, ultra-violet radiation, infrared radiation, X-rays, and gamma rays.

Show students a diagram of the electromagnetic spectrum. (A diagramof the spectrum can be found at Resource Button A on the CD-ROM.) Discuss the different forms of electromagnetic radiation in thespectrum. Point out that visible light is only a very small part of thespectrum. Play Video Clip 1 [47:14 to 49:02]. Discuss Sir WilliamHershel�s famous experiment. Ask students about other ways thatthey could verify the existence of infrared radiation. (They can feelheat from an object even though it appears normal�not glowing hot,etc.)

Explore (Approx. 45 minutes)Explain that students can detect infrared radiation in ways that can bemeasured.Students should work in small groups. You may wish to set up thering stands with thermometers and lenses in advance. Use the illustra-tion on Activity Sheet 1 as a reference. Students are going to focusinfrared radiation through a lens onto a thermometer. Studentsshould follow these directions for the set-up:� Clamp a 16d nail to a ring stand so that the nail head can be heated

by a Bunsen burner.� Attach a 5 cm focal length lens to a second ring stand. The lens

should be approximately the same height as the nail head.� To a third ring stand, clamp a thermometer so that the bulb is at

the same height as the lens and nail head. The nail head, lens, andthermometer should form a straight line. Approximately 5 cm(2 in) of space should be between the nail and the lens and 5 cmbetween the lens and the thermometer. The optimum postiondepends on the exact focal length of the lens.


Activity 1Try This

� Hold a flashlight by the nail head and hold a sheet of paper by thethermometer bulb. Shine the flashlight through the lens. Adjust thelocation of the flashlight and paper until the light beam is focusedon a sheet of paper. Adjust the thermometer so that the bulb is atthe exact focal point.

� On the ring stand, mark the location of the lens clamp. Move theclamp about 15 cm (6 in) up or down the ring stand so that the lensis no longer between the nail and the thermometer.

� Light the Bunsen burner and heat the nail head until it is red hot.� Record the temperature on the thermometer.� Move the lens back to its original position so that the focal point is

again on the thermometer.� After several minutes record the temperature on the thermometer.� Move the lens up or down the ring stand again and record the

temperature after several minutes.When the infrared radiation is focused on the thermometer, the tempera-ture should be several degrees higher than when the lens is moved away.After all groups are finished, discuss the results of the activity. Ask howmuch temperature variation students observed. Was the range the samefor all groups? What might have caused the differences in ranges fromgroup to group? Discuss what the experiment reveals about how heattravels.

Evaluate1. A piece of metal is so hot it glows yellow. As it cools, it turns red andfinally stops glowing. Is it still hot? Explain. (Yes, it�s still hot. While themetal is too cool to emit electromagnetic radiation in the visible spec-trum, it is still emitting infrared radiation, so it is still hot.)

2. Could infrared radiation have been discovered before the invention ofthe thermometer? Why or why not? (Yes; the discovery required thatsomeone notice that the area beyond the red end of the visible spectrumis warmer. Being able to measure temperature and seeing a spectrum witha prism helped scientists understand and quantify the effect.)

3. The lamp of a slide projector converts electrical energy into lightenergy. Does it do it efficiently? Why or why not? (No; the bulb pro-duces a fair amount of heat�infrared radiation�that is not necessary forviewing slides.)

Research Sir William Hershel’s famousexperiment. Using a prism, a thermom-eter, and sunlight, measure the tem-perature along the spectrum of visiblelight. Compare it to the temperature justbeyond the red. Record your observa-tions and data. Report your findings tothe class.

Obtain three light bulbs—standardincandescent, fluorescent, and halo-gen—that shine with comparablebrightness. Which one emits moreinfrared radiation? Which one is moreenergy efficient? Devise an experimentthat will answer these questions.Collect data and analyze it. Report yourfindings to the class.

Name___________________________________Name___________________________________Name___________________________________Name___________________________________Name___________________________________ Class Period_________ Class Period_________ Class Period_________ Class Period_________ Class Period_________

Copyright © Twin Cities Public Television & GPN. Permission granted to reproduce for classroom use.30 — Infrared

Activity 1 Sheet

focus on radiafocus on radiafocus on radiafocus on radiafocus on radiationtiontiontiontionWhaWhaWhaWhaWhat you�re going to do.t you�re going to do.t you�re going to do.t you�re going to do.t you�re going to do.You�re going to explore how infrared radiation can be focused and measured.

HoHoHoHoHow to do itw to do itw to do itw to do itw to do itWork with your group.

1 .1 .1 .1 .1 . Clamp a 16d nail to a ring stand so that the nail head canbe heated by a Bunsen burner.

2. Attach a 5 cm focal length lens to a second ring standat the same height as the nail.

3. To a third ring stand, clamp a thermometer so that thebulb is at the same height as the lens and nail head.The nail head, lens, and thermometer should form astraight line. Approximately 5 cm of space should

be between the nail and the lens and 5 cm between thelens and the thermometer.4. Hold a flashlight by the nail head and hold a sheet of paper by the thermometer bulb. Shine the flashlight

through the lens. Adjust the location of the flashlight and paper until the light beam is focused on the sheetof paper. Adjust the thermometer so that the bulb is at the exact focal point.

5. On the ring stand, mark the location of the lens clamp. Move the clamp about 15 cm up or down the ringstand so that the lens is no longer between the nail and the thermometer.

6. Light the Bunsen burner and heat the nail head until it is red hot.7. Record the temperature on the thermometer.8. Move the lens back to its original position so that the focal point is again on the thermometer. Record the

temperature on the thermometer every minute for five minutes.9. Move the lens up or down the ring stand again and record the temperature every minute for five minutes.

RecorRecorRecorRecorRecording your dading your dading your dading your dading your datatatatataRecord these variables in a table in your journal, alongwith any other observations you make during theexperiment.

Beginning temperature reading _______Temperature reading with lens:

Minute 1________ Minute 4________Minute 2________ Minute 5________Minute 3________

Temperature reading with lens removed:Minute 1________ Minute 4________Minute 2________ Minute 5________

Minute 3________

WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?What was the range of temperatures you recorded?

What effect did the lens have on temperature? Howdo you explain this?

What might be another way to test for infraredradiation?

Compare your data with the data of other groups.What might account for any differences?


Activity 2

Important Terms

Infrared Ray GunHow does a remote control work? What kind of signal does the remote control useto communicate with the TV? How is an infrared remote control similar to a flashlight? Can infrared radiation pass through glass like visible light does?

OverviewStudents use an infrared remote control to compare the characteristicsof infrared light and visible light. Students also investigate reflectionand transmission of infrared light.

ObjectivesAfter completing this activity, students will be able to�l describe physical laws that infrared radiation obeysl discuss the practical aspects of an infrared remote controll design a similar experiment relying on different properties of

electromagnetic radiation.

Time NeededPreparation: Approximately 20 minutesClassroom: Approximately 40 minutes

MaterialsFor each group of students:l penlight flashlightl mirrorl infrared remote control and the television or VCR it controlsl piece of black poster boardl pane of glass

Getting Readydigital signal — A series of electric orlight pulses.

Here’s How

32 — Infrared

Infrared


and cue the tape).l Gather the materials for each team of students.l Set up the televisions and remote controls.l Test the remote controls and penlight flashlights to make sure they

work.l Make a copy of Activity Sheet 2 for each student.l Review the information in the Background on page 24.


David Heil and Paul Kruse discusspractical applications of infrared

radiation. (2 min. 13 sec.)

Engage (Approx. 10 minutes)Hold up a TV remote control and ask the students what it is. Askthem if they know how it works. Encourage them to develop anddiscuss different theories.

Ask students if they can think of some other practical applications forinfrared radiation. Play Video Clip 2 [51:04 to 53:17]. Discuss some of theapplications shown in the clip. Remind the students that infrared radiation isa form of electromagnetic radiation. It is exactly like light, except it has alower frequency. Ask the students how they might determine if the infraredradiation coming out of a remote control behaves in the same way thatlight does.

Ask the students if they have remote controls at home. Does the remotecontrol have to be pointed directly at the TV to change channels? (no) Havethe students give suggestions as to how the remote control might workwithout being pointed directly at the TV.

Have the students discuss the properties of light. What do they know thatlight does and doesn�t do? Ask them to suggest ways that they could testinfrared radiation to see if it does or doesn�t do the same things. Suggestusing a remote control as a source of infrared radiation.

Explore (Approx. 40 minutes)Tell students they are going to experiment with a remote control and aflashlight to see how infrared radiation is similar to or different from light.

Students work in small groups. Each group should select an experimenter,a facilitator, and a data recorder. One or more students in the group can setup each of the activities.

Students find the remote sensor on the front of the television. Then they propthe poster board up in front of the TV, and make a mark on the part of theposterboard that covers the sensor.

l You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [46:28 to47:11]. Find out what studentsalready know about infrared radiation.As a class, discuss the questionsposed by Eileen Galindo.

l Make sure that none of the edgesof the glass pane are sharp. If theyare, cover them with masking tape.Remind students to handle the glasscarefully.

l This activity will be more success-ful if you can darken the room to makethe light from the flashlight morevisible.

l If possible, the first step could bedone with the flashlight—and later theremote control—resting on a desk ortable. However, this requires that theTV’s remote sensor be at the sameheight.

l If only one television and remotecontrol are available, split the classinto larger groups and assign a singleexperiment to each group.

l If any students have any respira-tory problems, they should avoidbreathing in concentrated airbornetalc.

l If it is appropriate, view the entireNewton’s Apple video segment oninfrared after completing the activity.

Guide on the Side


Try This

Activity 2Students prop the mirror up on a chair or desk, facing the TV. The experi-menter aims the pencil flashlight at the mirror so the reflection of the lightbeam strikes the poster board exactly on the mark. The experimenter doesnot move. The facilitator takes the flashlight out of his or her hands, andreplaces it with the remote control. The experimenter aims the remotecontrol at exactly the same place. The facilitator removes the poster board,and the experimenter presses a button on the remote control.

Next, students exchange the roles of experimenter and facilitator. They placethe remote control and the flashlight on a desk, pointed in the same direction.Both should be aimed at the TV. The facilitator places the poster board infront of the TV, then holds the pane of glass in front of the flashlight. Theexperimenter turns on the flashlight. The recorder notes whether the flashlightbeam travels through the glass. The facilitator then removes the poster board,and the experimenter presses the power button on the remote control. Therecorder notes whether the infrared beam travels through the glass.

Discuss the results of the activity. Ask team members whether the infraredbeam reflected off the mirror in the same way the light beam did. (yes) Didany substances block the light beam but not the infrared beam? (yes, thetalcum powder) Have students discuss why this might be. Remind them thatinfrared radiation is exactly like visible light, except it has a lower frequency.

Evaluate1. The TV in one room is hooked up to a VCR in the next room. Howcould you use the remote control to fast forward the VCR while you sat infront of the TV? (by setting up a mirror that would reflect the infrared beamonto the VCRs remote sensor)

2. Why doesn�t a remote control use a beam of visible light instead of a beamof infrared radiation? (Infrared light is invisible. If a remote control usedvisible light, turning on a light in the room could activate the television. )

3. How might you have determined whether infrared radiation will passthrough glass without using a remote control? (Answers will vary. Possibleanswer: Place a thermometer just inside a window and another one justoutside the window. Compare the readings.)

Try the same activity and shine thebeams of visible and infrared lightthrough a puff of talcum powder. Whatare the results?

Explore the reflection of light andinfrared radiation in more depth. Set upthe mirror, flashlight, and poster boardon a desktop covered with paper. Theflashlight should reflect off the mirrorand onto the poster board. Draw lines torepresent the angle of the light beamapproaching the mirror and leaving themirror. Repeat with the flashlight atdifferent angles. What rule can youdiscover?

Test the remote control and the flash-light further. Try blocking the beams withother materials, such as tracing paper,construction paper, clear plastic, etc.Can you find a material that blocks thelight beam, but not the infrared beam?Can you find a material that blocks theinfrared beam, but not the light beam?

Research other practical uses ofinfrared technology. Report yourfindings to the class.

Activity Sheet 2

Name __________________________________Name __________________________________Name __________________________________Name __________________________________Name __________________________________ Class Period ____________Class Period ____________Class Period ____________Class Period ____________Class Period ____________

Copyright © Twin Cities Public Television & GPN. Permission granted to reproduce for classroom use.34 — Infrared

Infrared RaInfrared RaInfrared RaInfrared RaInfrared RaygunygunygunygunygunWhaWhaWhaWhaWhat you�re going to dot you�re going to dot you�re going to dot you�re going to dot you�re going to doYou re going to test an infrared beam and a light beam under similar circumstances to see how they�re thesame and how they�re different.

HoHoHoHoHow to do itw to do itw to do itw to do itw to do it1. Work with your group. Select anexperimenter, a facilitator, and a datarecorder. Gather the materialsneeded for the activity.

2. Prop the mirror up on a desk ortable. Make sure it�s facing the televi-sion. Place the poster board in front of theTV and mark the spot directly infront of the TV�s remote sensor.Experimenter�Aim the flashlight sothat the beam reflects off the mirror and hitsthe mark on the poster board. Then be varycareful not to move. Once the remote control is inyour hands, aim it in the exact same direction andpress the power button.Facilitator�Once the experimenter has aimed theflashlight properly, carefully take it from his orher hand. Place the remote control in theexperimenter�s hand in exactly the same position.Then take the posterboard away from the TV.

3. Place the flashlight and the remote control on adesk. They should both be pointed at the TV. Youmay want to tape them down.Experimenter�Each time the facilitator places

something between the devices and the TV, testthe flashlight, then the remote control. Turn theflashlight on and then off. After the facilitator has

removed the poster board, press thepower button on the remote control.Facilitator�First hold the pane ofglass between the devices and the TV.Make sure the posterboard is in frontof the TV when the experimenter

tests the flashlight, and that it isn�t therewhen the experimenter tests the remote control.Data Recorder�For each test, record whether thelight beam and the infrared beam passed through thesubstance that was blocking it and reached the target.

WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?How are infrared and regular light similar?

How are infrared and regular light different?

Did your results match those of other groups?What might account for any differences?

What are some other ways you might test theproperties of infrared radiation?

RecorRecorRecorRecorRecording Yding Yding Yding Yding Your daour daour daour daour datatatatataSet up a table like this one in your journal, and recordthe following information.Blocking substance: _________________Light beam: passed ___ didn�t pass ___Infrared beam: passed ___ didn�t pass ___

Other observations:


Activity 3

Getting Ready

As Clear As GlassWhy do plants grow in a greenhouse during the winter? What happens inside a carwith rolled-up windows on a sunny day? Does sunlight always pass through glass?Does infrared radiation from the sun always pass through glass? What is thegreenhouse effect?

Important Terms

OverviewStudents compare the transmission of infrared radiation through apane of glass with the transmission of infrared radiation in and out ofa closed glass container.

ObjectivesAfter completing this activity, students will be able to�l conduct an experiment using a control and analyze the resultsl discuss how wavelength affects the transmission of infrared

radiationl explain why plants can grow in greenhouses in cold weather.

Time NeededPreparation: Approximately 10 minutes.Classroom: Approximately 70 minutes.

MaterialsFor each group:l 3 thermometersl small pane of glassl wide-mouthed glass jar large enough to completely hold and

enclose one of the thermometers

greenhouse — A small glass buildingin which plants are grown.

Here’s How

36 — Infrared

Infrared


and cue the tape).l Gather the materials for each team of students.l Make a copy of Activity Sheet 3 for each student.l Review the information in the Background on page 24.


Maj. Matt Ferrin shows film of movingvehicles taken through an infrared“thermal sight” on a tank. (56 sec.)


David Heil and Paul Kruse discussinfrared radiation, visible light, and the

electromagnetic spectrum.(1 min. 1sec.)

Engage (Approx. 10 minutes)Hold your hand near a sunny window or a burning light bulb. Ask studentsto explain why you feel heat. (Infrared radiation from the sun orfrom the bulb is striking your hand, and you feel it as heat.)

Show Video Clip 3 [50:08 to 51:04]. Ask why the vehicles show up sobrightly on the infrared viewer. (Objects that are hot show upbrightly, and the vehicles are producing a lot of heat.) Have studentsrecall what happens inside a car parked in the sun with the windowsrolled up. Have students tell why this might happen. Is it for the samereason that the vehicles in the video were hot? (No, because thosevehicles� engines were running. A car in a parking lot is not producingheat, it�s being heated by infrared radiation from the sun.) Whatwould happen in the same car with the windows rolled down? (Itwouldn�t get as hot.) Why? Begin a discussion as to what role thewindow glass plays in the heating of the car.

Ask students to think of a greenhouse. Plants can grow in a greenhouse inthe winter, because the interior of the greenhouse stays quite warm. Theglass in the greenhouse serves the same purpose as the windows in the car.Play Video Clip 4 [49:02 to 50:03]. Lead students to understand thatall objects emit infrared radiation, but that hotter objects emit moreinfrared radiation, and radiation with a higher frequency. Havestudents discuss how that fact, combined with the properties of glass,might allow a greenhouse to heat so well.

Explore (Approx. 60 minutes)Tell students they are going to experiment with glass to determine how itaffects heating.

Students work in small groups. Each group should select a data recorder.One or more students in the group can set up the activity. Each groupshould be assigned a section of window sill.

Guide on the Sidel You may wish to begin the lessonby viewing the Introduction from theVideo Menu on the CD-ROM [46:28 to47:11]. Find out what students alreadyknow about infrared radiation. As aclass, discuss the questions posed byEileen Galindo.

l Make sure that none of the edgesof the glass pane are sharp. If theyare, cover them with masking tape.Remind students to handle the glasscarefully.

l If the sun is not shining on theclassroom’s window sill, you can havestudents place their setups underlamps containing 100-watt or 150-wattbulbs. All three thermometers shouldbe an equal distance from the bulb,and as close as possible to it. Even ifthe window sill is sunny, you mighthave one or two groups use lampsinstead, then compare the results ofthe various groups.

l If it is appropriate, view the entireNewton’s Apple video segment onInfrared after completing the activity.


Activity 3Try This

If possible, students should open the window slightly, so the glass in thewindow does not affect the experiment. Students first place one thermometeron the window sill. Then they prop the pane of glass up in the windowopening. They should place the second thermometer so that sunshine mustpass through the pane of glass to reach it. Students place the third thermom-eter inside the glass jar and invert it on the window sill. All three thermom-eters should be at about the same angle to the sun.

The recorder notes the reading on all three thermometers at the beginning ofthe experiment. He or she then rechecks the readings every five minutes foran hour.

Discuss the results of the activity. Ask team members which thermometerregistered the highest temperature. (the one in the jar) Did the presence of glassalone affect the reading of the thermometers? (The thermometer behind thepane of glass may have read slightly higher than the first thermometer, but itwasn�t nearly as high as that of the thermometer inside the jar.) Have studentsdiscuss why the glass jar caused a much greater increase in temperature thanthe pane of glass.

Ask whether infrared radiation from the sun can penetrate the glass. (yes)What happens when that radiation strikes the thermometer and the air aroundit? (They get warmer, so they emit more infrared radiation.) How is infraredradiation from the sun different from infrared radiation emitted by thethermometer and the air around it? (Infrared radiation from the thermometeris weaker and has a lower frequency.) How might that account for the highertemperature inside the jar? (The low-frequency infrared radiation cannotpenetrate the glass, so it stays inside the jar, increasing the temperature.)

Evaluate1. What purpose did the first thermometer serve in this experiment? (It was acontrol to show the temperature with no glass involved, in order to provide abasis for comparison.)

2. A group of scientists is setting up an experiment involving low-frequencyinfrared radiation. The lab is refrigerated, so only the apparatus will producemuch infrared radiation. They need to make sure that no low-frequencyinfrared radiation enters the lab and confuses their readings. The lab has awindow. Do they need to block it off? Why or why not? If they do, whatshould they use? (They don�t need to block the window off, because low-frequency infrared radiation does not penetrate glass.)

3. How does a greenhouse keep plants warm in the winter? (High-frequencyinfrared radiation from the sun enters the greenhouse. It is absorbed by the air,the plants, the dirt, and the floor, making them warmer. They emit anincreased amount of low-frequency infrared radiation. This radiation cannotpenetrate the glass, so it stays in the greenhouse. It is re-absorbed by the air, theplants, the dirt, and the floor, making them even warmer.)

Repeat the experiment using glassbottles and jars of different colors.Which color traps the most infraredradiation inside? Test other materials,such as transparent plastic and opaqueplastic.

As certain gases build up in theatmosphere, they change the propertiesof the atmosphere. Specifically, theychange the way the atmosphere letscertain frequencies of radiation through,and doesn’t let others through. This issometimes called the GreenhouseEffect. Describe, based on this experi-ment, how you think the GreenhouseEffect works. Check your answers bydoing research on the GreenhouseEffect.

Invite the manager of a local green-house to speak to the class about howthe greenhouse works.

Activity Sheet 3

Name____________________________________ Class Period ____________Name____________________________________ Class Period ____________Name____________________________________ Class Period ____________Name____________________________________ Class Period ____________Name____________________________________ Class Period ____________

38 — Infrared

AAAAAs Clear as Glasss Clear as Glasss Clear as Glasss Clear as Glasss Clear as Glass

WhaWhaWhaWhaWhat you�re going to dot you�re going to dot you�re going to dot you�re going to dot you�re going to doYou re going to test how infrared radiation passes through glass in different situations. Which one gets thehottest?

HoHoHoHoHow to do itw to do itw to do itw to do itw to do itWork with your group. Open the window so the sun shines on the sill without passing through the windowglass. Place a thermometer on the window sill. Prop a pane of glass up in the window opening and place asecond thermometer behind it. Sunlight should pass through the glass to reach the thermometer. Place athird thermometer in a glass jar with a lid and set it on the window sill.

Data Recorder � Record the temperature on all three thermometers as soon as they are put inplace. Check and record the temperatures every five minutes for an hour.

RecorRecorRecorRecorRecording your dading your dading your dading your dading your datatatatataSet up a table like this one in your journal, and record the following information:

Readings at ___ minutes into experiment.

Thermometer #1: ___ degrees



WhaWhaWhaWhaWhat did you find out?t did you find out?t did you find out?t did you find out?t did you find out?Which thermometer showed the greatest increase in temperature?

Did infrared radiation from the sun penetrate the glass? How doyou know?

How was the setup in front of the pane of glass different from theone inside the jar?

What does this tell you about high- and low-frequency infraredradiation?

Graph your data. Does this help you analyze your results?


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Credits

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40 — Credits

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AT LAST, a supplemental middle school science curriculum that helps you meet the challengesof today�s science classroom. The program engages students by incorporating segments fromthe award-winning Newton�s Apple television show into hands-on/minds-on activities. Eachlesson plan helps you integrate the technology using an inquiry-based approach. A variety ofassessment options allow you to gauge student performance. And the entire program is corre-lated to the National Science Education Standards.

EACH CURRICULUM MODULE CONTAINS:● a CD-ROM with two Newton�s Apple segments, a video profile of a working scientist,

and additional audio/visual resources● a teacher�s guide with lesson plans for six inquiry-based activities

● a Newton�s Apple videotape

38 topics in 19 modules!! Choose the curriculum modules that benefit your needs.Physical Science Life Science and Health Earth and Space ScienceAir Pressure/Domed Stadiums Antibiotics/Cancer Clouds/WeatheringElectric Guitars/Electricity Blood Typing/Boner Dinosaur Extinction/EarthquakesGravity/Rockets DNA/DNA Fingerprinting Everglades/SewersInfrared/Reflection Hearing/Human Eye Geothermal Energy/Glaciers

Nicotine/Smiles Greenhouse Effect/OzoneSports Physics Meteors/Solar EclipsesHang Gliders/Surfing Phases of the Moon/The SunHigh Wire/SkateboardsSpinning/Water-skiing

Individual Packages: $49.95 To order by mail: To order by phone, call toll-free:Three-CD collection: $119.45 1-800-228-4630Four-CD collection: $159.95 Fax your order to:

1-800-306-2330E-mail your order to:

P.O. Box 80669 [email protected], NE 68501-0669

Box 80669, Lincoln, Nebraska 68501 � 800-228-4630

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