Diffraction of Waves in English Learning

Diffraction

1. CHAPTER 5 : WAVES PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

2. The bo y able to hear sound from the radio place d a t the oth e r side o f t h e wall. Smal l boat s o n cal m water. Meanwhile in the middle o f t h e sea, a boa t i s mo v ing u p and down. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

3. S o u r ce: Im a ge ©2 019 T e r r a Met rics Im a ge ©2 019 M a x ar T echn o logies Photograp h shows the embankme n t buil t in M aran g , Tereng gan u . The wa v efron t o f the seawater changes from pla n e wavefront in region A to circul a r wave f ront in region B. W h a t cau s e s the wave f ront o f the seawat e r in region A an d r egio n B t o hav e differen t sh apes? Se a wa v e s sp r ea d ou t while p r opa g at i n g th r oug h the gap in the embankment. This phenomeno n is called a s DIFFR A CTION o f waves. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

4. Diffraction of wav e s can ha p pen to… Water wa v es Li g h t waves Soun d w av e s PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

5. Diffraction o f wav e s is the SP R EAD ING of WAV E S wh e n the w av e s propagate THROUGH a SLIT o r si d e o f a BA R RIER. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES WHAT IS DIFFRACTION?

6. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

7. Apparatu s: Ripple tank an d its acces s orie s, digital x e non stroboscope and bar r iers Mate r ial s: Distilled water Inst r uction s : Se t u p the apparatu s a s shown. Adju st the speed o f t h e ripple gener ator so that waves ca n b e seen clea r ly o n the screen u s ing the st r oboscope. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

8. Place the b a r r iers to form a ga p with size almos t simi l a r to the wav e length o f the wa v e p rodu ced. S w itch of f the ripple generato r an d wait unti l the w ate r in the ri p ple tank become s calm. Switch o n the ripple gener ator ag ain. Obser v e the shape o f the w av e front b ef o re an d afte r p as s ing th r oug h the gap. Draw the sha p e o f the wa v efron t afte r pa ssi n g th r oug h the ga p an d record the c haracteri s tics o f the w av e front bef o re an d afte r pa ssi n g th r oug h the ga p in a table. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

9. Observation: PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES The water wa v e s sp r ea d ou t after passing th r oug h the gap. The incident wave is a plane wave, while the diffracted wave is a circular wave.

10. Result s : Complete the patte r n o f the water wav e s afte r pa ssi n g th r ough the gap . Compare the shape o f the incident wa v efron t with the diffracted wav e front. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

11. Discus s ion: The diff racted wa v e s is s p read ou t to a wider are a . Energ y o f t he wa v e s reduced, therefore amp l itude decrea s ed. Incident wa v e Diffracte d wa v e Characteristic o f wave Comparison before an d afte r the gap Wavel e ngth , λ Equal Frequency, f Equal Wave speed, v Equal Amplitude, a Decrease s Directio n o f p ropag a tion Spread out PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

12. Apparatu s: Laser pen , retort stan d , si n gle na r row s lit, single wide slit, small sized pin hole, la r g e sized pin hole an d white sc r een Instructions: Se t u p the app ara t u s a s shown. U s e a si n gle wide slit. Direc t the las e r light ray th r oug h the si n gle sli t . Ob s erve t h e pattern formed o n the screen an d draw the pattern in a t a ble. Repea t steps 1 a n d 2 u s ing: a si n gle na r row slit (b) a la r g e pin hole (c) a sma l l pin hole PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

13. Result: Single wide slit Single na r row s l it La rge pin hole Smal l pin hole PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

14. Appa r atus: Tablet, small loudspeaker that ca n be connecte d to tablet . Instructions: Set u p the apparatu s a s shown a t a corne r o f a building. Scan the QR co d e to downl o a d the sound gener a tor applicatio n from the website given. Generate a sound o f frequency o f 50 H z from the application. Stand a t positio n X a s shown in Figure 5.4 8 an d listen to the soun d from th e loudspeaker. Repea t step 4 b y standing a t positio n Y. Recor d you r observation s in a table. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

15. Result: Disc us s ion: Can the sound from the loud s peake r b e hea r d at posi t ions X a n d Y? Explain why s oun d ca n be hea r d a t posi t ion Y eve n t h ough the loudspeaker canno t be seen. Position Soun d hea r d X Yes Y Yes PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES Sound wave diverge s and spread ou t to a wider region.

16. Ef fect s o f the diff raction o n c haracteri s tics o f wa v es Char a cteristi c of wave Chan g e cause d by diffraction Explanation W a v e length No chan g e W a v e s pee d doe s no t ch a n g e F r equency No chan g e No chan g e to so u rce of freque n cy Speed No chan g e No ch a n g e in me d ium befo r e an d afte r diffraction Amplitude Decrea s e s W a v e ener g y diverge s and s p re a d ou t to a wider re g ion Directio n o f p ro p ag a tion F r o m on e di r ectio n to many di r ections W a v e front s p re a ds PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

17. C PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES B

18. Diffraction Amplitu d e dec r eases. Wave energ y diverge s and spread ou t to a wider region. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

19. λ Spre a din g o f wa v e s when the wa v e s p r opa g ate th r oug h a s lit o r s i d e o f a ba r r i er. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

20. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

21. Appa r atus: Rippl e tank an d its accessories , digita l xeno n stroboscope an d barriers Mater i als: Distille d water Instructions: Prepar e the ripple tank an d switch o n the ripple generator. Observe the wavelength o n the glas s screen. Adjust the size o f the slit so that it is larger than the wavelength. Obser v e the diffracte d wave an d dra w the patter n in the table. Repea t steps 3 an d 4 with a slit size that is almos t the same a s the wavelength. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

22. Siz e o f slit Patter n o f d iffraction Sketc h o f wav e front Wi d e s lit Na r r o w s l it Result: PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

23. Appa r atus: Rippl e tank an d its accessories , digita l xeno n stroboscope an d barriers Mater i als: Distille d water Instructions: Adjust the size o f the slit to abou t 1 cm. Adjust the frequency o f the ripple generato r to produc e a wavelength shorter than the size o f the slit. Obser v e the diffracte d wave an d dra w the patter n in the table. Repea t steps 2 an d 3 usin g a wavelength that is almos t the same a s the size o f the slit. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

24. Result: Wavelength Patter n o f d iffraction Sketc h o f wav e front Short er Long er PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

25. Discus sion: Compare the pattern s o f diffracted waves through a wide slit an d a narrow slit. Wide slit : Sprea d ing o f waves is less signifi c ant Narrow slit : Spreading o f waves is more significant Compare the pattern s o f diffracted waves o f short an d long wavelengths passing through a slit. Short λ : Spreading o f waves is less significant Long λ : Spreading o f waves is more significant PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

26. C PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

27. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

28. Effects o f diffractio n o f waves Fixed wavelength Fixed size o f slit Wide gap Diffractio n less significant Small gap Diffractio n more significant Short wavelength Diffractio n less significant Long wavelength Diffractio n more significant PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

29. Slit 0.0 2 mm Slit 0.0 4 mm Single wide slit : V er y brigh t light in the middle. Single narrow slit : D ar k an d brigh t lines alternately . Brighte r in the middle. Slit 0.0 8 mm Slit 0.1 6 mm The light wave diffraction’s pattern passing through a single slit o f variou s size PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

30. Befor e the gaps , the wavefronts are straight/ plan e for bot h diagrams. After pas s through the gaps , the wavef r ont s is more circula r for narrow ga p an d less circula r for wide gap. The wavelength equa l befor e and afte r passin g thr o ug h t h e gap s for bot h diagrams. The smaller the gap , the more circula r th e wav e pattern. Ph y sics con c ep t is diffractio n. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

31. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

32. 1 . A p ai r o f b a r r i er s is buil t to protect hou s ing a r e a nea r a beach. ( a ) Comp a re the ampli tu d e o f t h e sea wave befo r e a n d a fter p a s s ing th r oug h t h e wall openin g . Amplitude decreased ( b ) B y rel a ti n g the s ize o f the wave with the ener g y , explai n ho w t he ero s ion ef f ec t o f t h e beac h a r ound the hou s ing a r e a ca n b e re d uced b y t h e b arr ie rs . Buil d barrier s with small openin g so that diffractio n ca n occur. Energy o f the waves is reduced a s waves spread ou t to larger are a afte r passin g the ga p. Ampli t ud e o f the waves d e creas e d. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

33. 2 . Diffractio n o f water waves produce s cal m water regions, suitable for docki n g o f ships an d water recre a tional a ctivitie s. Barriers Gap Calm water region PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

34. 3 . Owls ar e abl e to communicat e acros s long distance s in the forest becaus e they hav e long wavelengths hoots . Explain. The sound o f the owl s will diffrac t through the space betwee n trees in the forest. The longer wavelength o f the hoot s also easie r to b e diffracted. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

35. 4 . Infras o ni c w a ve s produ c e d by elephant s hav e long wavelength to facilitate long distance communicatio n between elephants. 5 . Diffrac tion o f light waves can produc e hologram s which are use d a s safety features o n bank card s suc h a s debi t card s and credi t cards. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

36. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

37. 11 . Diagra m 11 .1 an d Diagra m 11 .2 show a wa v e phenom e no n afte r w ate r w av e s pa s s i n g th r oug h ga ps o f different s i zes an d the ampl i tude a , o f the wa v es. (a) Name th e wa v e phenomeno n in Diag r a m 1 1 .1 an d Diag r a m 1 1 . 2 . Diffraction [1m] Usi n g Diag r a m 1 1 .1 an d Diag r a m 1 1 . 2 , com p a r e th e s ize o f t h e g a p , the a n gle o f waves' sp reading an d the am plitud e of the wa v e afte r p as s ing th r oug h the ga ps. [3m] PAPE R 2 -SECTIO N C [20 m ] Size o f the ga p in Diagra m 11 .1 > Diagra m 11 . 2 . Angle o f waves' sp reading in Diag r a m 1 1 .1 < Diag r a m 1 1 . 2 . Amplitude o f th e wa v e afte r p as s ing th r oug h the ga ps in Diag r a m 1 1 .1 > Diag r a m 1 1 . 2 . Diagra m 11. 1 Diagra m 11.2 PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

38. (i i ) relate the s i ze o f t h e ga ps with the an gle o f wa v es ' sp reading an d the an gle of the w av e s' sp r eadin g w ith the amplitud e o f the w av e s. [2m] Size o f the ga ps decrea s es , the an gle o f waves' sp reading incr ea s es. Angle o f th e wa v es ' sp reading incr ea s es , the ampl i tude o f the wa v e s decrea s es. (c) Diag r a m 1 1 .3 sh ow s a n incid en t water wa v e s pa s s i n g th r oug h the end s o f a floating wo o d . Copy Diag r a m 1 1 .3 an d d r aw the water wa v e s afte r p as s ing th r ough the end s o f the floating w ood . Mark w ith (X) the region w her e the w ate r is calm . [4m] X Diagra m 11.3 PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

39. (d) Diag r a m 1 1 .4 sh ow s a co m munication sy s tem invol v e d in the tra n s mis s ion o f r adi o b r oadca s ts through hilly t e r r ain . Wa v e is transmitted from the tra n s mitter an d recei v e d b y the hou s e s behi n d the hill s . H o we v er , the s i gn al received is no t clear. Y o u ar e requir e d to giv e some s uggestion s to de sign a communica t ion sy s tem w hic h can imp r o v e the qu ality o f s ignal tra n s mis s ion. Usi n g the knowledg e o n wa v es , e x pla i n your sug gestion s ba s e d o n t h e foll ow ing as p ects; type o f wave tra n s mitted, frequency o f the wa v e, wa v elengt h o f th e wa v e tra n s mitted, location of the tra n s mitter an d t h e method invol v e d which enab l e the wa v e to p r opag a te in a longer di s tance. [10m] Diag ram 1 1.4 PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

40. SUGGESTION EXPLANATION Type of wave transmitted: Radi o wave Can propagat e in long distance Frequency o f the wa v e: Hig h wave frequ e ncy Ha s hi g he r e n ergy Wavelength of the wave transmitted: Longer Diffrac tion o c cur s a t a larg e r a ngle / Eas y to diffract L ocation o f the transmitter : At h ig h ground Can transmit radio waves without an y obstacles / Signal s no t block Method invol v e d which enab l e the wa v e to p r opag a te in a longer di s tance: Usin g relay stations To amplif y the signal / T ransmit signal to a furthe r dis t ance PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES

41. PHYSICS FORM 4 KSSM DUAL LANGUAGE PROGRAMME | CHAPTER 5 WAVES| 5.4 REFRACTION OF WAVES