pwb chapter 9

8/3/2019 PWB Chapter 9

http://slidepdf.com/reader/full/pwb-chapter-9 1/16



Name: Class: Date:

Herearetwohypothesesabouthowweseethisbook:

• Lightmusttraveltooureyesfirstandthentothebook.

• Lightmusttraveltothebookfirstandthenisreflectedintooureyes.

Whichhypothesisdoyouthinkiscorrect?

Activity 9.2 How Do We See this Book?

Aims• Totesttwohypothesesabouthowwe

seethings

Apparatus and materials• Torchorlamp,cardboardtubeorlargeboard

Key skills and competencies• Skills:using apparatus and equipment,

observing

• CIT:creativity (planning an investigation),

sound reasoning

Link i t



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C h a p t e r 9

Plananexperimentthatwilldeterminewhichofthetwohypothesesiscorrect.You

maywishtouseatorchandacardboardpapertubeorlargeboard(toblockoutlight).

1. Method

Describeyourmethodinthespacebelow.Besuretoexplainhowtocarryoutafair

test.Usediagramstohelpyou.

Checkyourmethodwithyourteacher.Next,carryoutyourexperiment.

2. Observations

3. Conclusion

Whichhypothesisdotheresultssupport?

E.g.

To test hypothesis A, use a cardboard tube or a board to block out light and make the light travel asshown. Observe if the book can be seen clearly.

To test hypothesis B, set up the cardboard tube or board as shown. Again, observe if the book can beseen clearly.

The book can be seen clearly when light from the torch is shone directly at it but not seen clearly when

shone directly into the viewer’s eyes.

Hypothesis B

tube

board

or

tube

board



Name: Class: Date: Activity 9.3 Investigating Reection in a Plane Mirror

Aims• Toinvestigatethereectionoflightina

planemirror

Apparatus and materials• Rayboxwithslitandpowersupply,paper

sheetwitha180°protractordrawnonit

Forthisexperiment,youwillbegivenasheetofpaperwitha180°protractordrawnonit.

1. Placethebackofaplanemirroronthepaperasshown.

Thelineatrightanglestothemirroriscalledthenormalline.

Key skills• Skills:using apparatus and equipment,

measuring

Link i t

2. Usearayboxtoshinearayoflightontothemirrorat20°fromthenormallineas

showninthediagram.

Thisrayiscalledtheincident ray.

Theangleof20°iscalledtheangle of incidence(i ).

3. Canyouseeareflectedrayoflight?

Measuretheanglebetweenthenormallineandthereflectedray.

Thisiscalledtheangle of reflection(r ).Recordthevalueofr inthetableonthe

nextpage.

normal line

ray box

0

0 1 8 0

9 0

1 8 0

Yes



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C h a p t e r 9

4. Repeatusingotheranglesofincidence.Recordyourresultsinthetable.

5. Prediction Iftheangleofincidenceis35°,whatwilltheangleofreflectionbe?

Testyourpredictionbydoinganexperiment.

Whatwastheresultfortheangleofreflection?

6. Conclusion

Completethefollowingsentence:

Theangleofincidenceis (equalto/largerthan/smallerthan)theangleofreflection.

Angle of incidence (i ) Angle of reection (r )

35˚

35˚

20˚ 20˚

equal to



Name: Class: Date: Activity 9.4 Investigating Phases of the Moon

Aims• Tobuildamodeltoinvestigatethe

appearanceoftheMoonatdifferenttimes

ofthemonth

Apparatus and materials

• Tennisball,torchorlamp

Key skills and competencies• Skills:using apparatus and equipment

observing

• CIT:creativity (designing a model)

Link i t

(A) Observing the Moon

1. LookattheMooneachnightatabout9.00pm.

2. Inthetablebelow,drawhowthephasesoftheMoonchangeover30days.Write

inthedateasshownintheexample.

Day 1 3 52 4 6

Phase

Date

Day 7 9 118 10 12

Phase

Date

Day 13 15 1714 16 18

Phase

Date

Phase

2 May Date



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C h a p t e r 9

(B) Modelling the phases of the Moon

Method

Questions

1. HowareweabletoseetheMoon?

2. ExplainhowweareabletoseethedifferentphasesoftheMoon.

Day 25 27 2926 28 30

Phase

Date

You are given a tennis ball and a lamp or torch. In groups, discuss how you would be able

to demonstrate the phases of the Moon as seen on Earth. Describe your method below or

draw a diagram to show your set-up.

Day 19 21 2320 22 24

Phase

Date

1. One student should hold the torch (represents the sun). Another student should hold the tennis ball

(represents the Moon). Another student can represent the Earth.

2. The students representing the Sun and the Earth should face each other. The student with the ballshould stand in between them.

3. The student representing the Earth should rotate on the spot. As he or she does this, the student withthe ball should revolved around the student representing Earth.

We are able to see the Moon because it reects light from the Sun.

We see different phases of the Moon because as the Moon orbits the Earth, different parts of it reect light

from the Sun.



Name: Class: Date: Activity 9.5 Investigating Images in Plane Mirrors

Aims• Toinferthecharacteristicsofimagesformed

inplanemirrors

Apparatus and materials• Sheetofglass,mirrorholder,whitescreen

(orsheetofpaper),twoBunsenburners,smallplanemirror,plasticsheet

Inthisexperiment,asheetofglassisused.Theglassactspartlyasaplanemirroralthoughit

istransparent.

1. Placeasheetofglassuprightonthetable.

PlaceaBunsenburnerinfrontofit.

2. Lookintothe‘mirror’toseetheimageofthe

Bunsenburner.

(a) Istheimageuprightorinverted?

(b) Istheimagebigger,smallerorthesamesize

astheobject?

3. Placeawhitescreenorsheetofwhitepaperbehindtheglass.Moveitbackwardsand

forwardstotrytogettheimageonthescreen.


observing

• CIT:sound reasoning

Link i t

sheet of glass

white screen

Canyougetanimageonthescreen?

The image is upright.

The image is the same size as the object.

No



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C h a p t e r 9

Istheimageinthemirrorturnedsideways?

Whatisthiscalled?

6. Conclusion

Fromyourobservations,statefivecharacteristicsoftheimageformedbyaplane

mirror.

4. (a) MoveanotherBunsenburnerbehindtheglassuntilitisexactlyalignedtotheimage

ofthefirstBunsenburner.MeasurethedistancesofthetwoBunsenburnersfrom

theglassmirror.

Whatdoyounoticeaboutthedistancesoftheobject(thefirstBunsenburner)and

theimage(thesecondBunsenburner)fromtheglass?

(b) RepeatwiththeBunsenburnerplacedatdifferentdistancesfromtheglassmirror.

Istheresultthesame?

5. (a) Writeawordonaclearplasticsheet.

(b) Holdthesheetinfrontofaplanemirror.

Canyoureadtheword?

Onthediagram,drawwhatyouseeontheplasticsheetandinthemirror.

plastic sheet plane mirror

1. The image is upright.

2. The image is the same size as the object.

3. The image cannot be formed on a screen that is behind the mirror.

4. The distances of the image and the object from the mirror are equal.

5. The image is laterally inverted.

Yes

Lateral inversion

The two distances are the same.

Yes

Yes



Name: Class: Date:

narrow beam

of light

Activity 9.6 Investigating Refraction

Aims• Toobservewhathappenswhenlightpasses

throughablockofglass

Apparatus and materials• PartA: Round-bottomedask,highintensity

torchorlaserlight,uorescein(orcoffee-mate)solution,sourceof

smoke(e.g.stickofincense)

(A) [DEMO] Bending light

1. Setuptheapparatusshowninthediagram.

Tomakelightvisible,addfluorescein(orcoffee-mate)tothewaterandintroducesomesmoketotheairabovethewater.

2. Allowanarrowbeamoflighttopassfromairtowater.

Thebeamoflight

(bends/doesnotbend).

• PartB: Rectangularglassblock,raybox,

sheetofwhitepaper(A4),pencil


observing

• CIT:sound reasoning

Link i t

(B) How does light move through glass? o p t i o n al f o

r

N ( A )

1. Placeaglassblockonasheetofwhitepaper.Useapenciltodrawtheoutlineofthe

block.

2. Usearayboxtoshineanarrowbeamoflightintotheglassblockasshownbelow.

sheet of white paper

sheet of white paper

ray boxglass block

bends



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C h a p t e r 9

Canyouseetherayinsidetheglassblock?

Doesthelightbendwhenitenterstheglassblock?

Lookfortheraycomingoutoftheglassblock.

Doesthelightbendagainwhenitcomesoutoftheglassblock?

3. Lookthebeamsoflightonthepaper.Onthepaper,drawtwocrossestoshowthe

pathoflightgoingintotheblockandtwomorecrossestoshowthepathoflight

comingout.

4. Removealltheapparatus.Usearulertojointhecrossestoshowthemovementof

thelight.Also,drawthetwonormalsatrightanglestotheglassblock.

5. Conclusion

Completethefollowingsentences.

(a) Lightmovingfromtheairintotheglassisbent(orrefracted)

(towards/awayfrom)thenormal.

(b) Lightmovingfromtheglasstotheairisrefracted

(towards/awayfrom)thenormal.

away from

towards

Yes

Yes

Yes



Name: Class: Date: Activity 9.7 How Are the Colours in a Rainbow Formed?

Aims• Toobserveaspectrumofwhitelight

Apparatus and materials• Raybox,twoglassprisms,whitescreen

1. Setuparayboxandaprismasshowninthediagram.

2. Shineabeamoflightthroughtheprismandontothescreen.

Youshouldseesomecoloursonthescreen.(Youmayhavetoturntheprismtoseethe

coloursclearly.)

Listthecoloursyouseeonthescreen,startingfromthecolournearestpointX.

3. Placeasecondprismasshowninthediagrambelow.

Key skills• Skills:using apparatus and equipment,

observing, inferring

Link i t

X

ray box

prismscreen

(a) Whatcolourisformedonthescreennow?

White

Red, Orange, Yellow, Green, Blue, Indigo, Violet



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C h a p t e r 9

(b) Whathasthesecondprismdone?

Questions

1. Whatismeantby‘whitelight’?

2. Whatwordisusedtodescribethesplittingofwhitelightintoseparatecolours?

3. (a) Whichcolourisbentthemostbytheglassprism?

(b) Whichcolourisbenttheleastbytheglassprism?

4. Nameoneeverydayphenomenonthatinvolvesthesplittingofwhitelightintocolours.

Light that is a mixture of all the colours of the spectrum (and which we see as colourless)

Dispersion

Violet light

A rainbow/Colours on (soap) bubbles

The second prism has recombined the colours of the spectrum.

Red light



Activity 9.8 How Do Objects Appear in Light of Different Colours?

Aims• Toobservehowobjectsappearinlightof

differentcolours

Apparatus and materials• Rayboxortorch;red,greenandbluelters

tottherayboxortorch;white,red,greenandblueobjects

1. Shinewhitelightfromarayboxortorchontowhite,redandgreenobjects(ina

darkenedroom).Notethecolourstheobjectsappearin.Recordyourresultsinthetable

givenbelow.


observing, predicting

• CIT:creativity (testing predictions)

Link i t

Colour of light shining on the object

White Red Green Blue

White White

Red

Green

Colour of object

in daylight

o p t i o n al f o

r

N ( A )

Name: Class: Date:

2. Placearedfilterinfrontoftherayboxoroverthetorch.Shinetheredlightontoeach

objectandagain,notethecolourtheobjectsappeartobe.

3. Repeatusinggreenfilters.

4. Results

Completethetablewithyourobservations.

ray box

object

Red

Red

Black

Green

Black

Green

Blue

Black

Black

Red

Green



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C h a p t e r 9

5. Making and testing predictions

Youwillnowuseyourunderstandingofcolouredlighttomakepredictions.Youwillthen

doanexperimenttotestthepredictions.

(a) Whatcolourwillablueobjectappeartobeinlightofthefollowingcolours:white,

red,greenandblue?Recordyourpredictionsinthetablebelow.

(b) Testyourpredictionsbydoinganexperiment.Recordyourobservationsinthetable.

(c) Wereyourpredictionscorrect?

Questions

1. Inwhatcolouroflightisanobjectthesamecolourasitisindaylight?

2. Underwhatconditionsdoesacolouredobjectappearblack?

3. Whatdoscientistsdoifexperimentsshowthattheirpredictionsarewrong?

Colour of light shining on a blue object

White Red Green Blue

Predicted results

Experimental results

(Blue)

Blue

(Black)

Black

(Black)

Black

(Blue)

Blue

Yes/No

In white light and in light of the same colour as that of the object

An object appears black when the light shone on it is absorbed and not reected at all.

E.g. Scientists can conduct more experiments, modify their models/ideas or rene their predictions.

pwb chapter 9

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