1.3 refraction of waves editted

7/25/2019 1.3 Refraction of Waves Editted

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1.3 ANALYSING REFRACTION OF WAVESa) Refraction of water wave!") Refraction of #i$%t wave!c) Refraction of o&n' wave.

Intro'&ction (1. Refraction of waves ;

- When a wave traveling in one medium crosses the boundary into amedium where its velocity is different, the transmitted wave may move ina different direction than the incident wave.

2. ffect of refraction of waves ;

a) Refraction of water wave (1. when a water wave travelling from dee! area to shallow area.

Ri!!le tan"

- 1 -

v, #velocity$ will change after refraction.

f, #fre%uency$ same before and after refraction.

&, #wavelength$ will change after refraction.


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2. 'he characteristics of the refracted of water waves are as below ;

& & dee! ( & shallow

f same before and after refraction # f ) constant $,

v v dee! ( v shallow

*hallow area Refracted near to normal line. #angle of i + $

ee! area Refracted far from normal line. # i + $

f ) constant f ) v &v1 &1 ) v2 &2

/. 0 !attern of refraction of water waves.- different ty!es of trans!arent !late!ers!ecs !late.

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") Refraction of #i$%t wave (

1. When a light wave travelling in one medium crosses the boundary into amedium with different density where it velocity is different.

2. v ) at low density medium.

/. v ) at high density medium.

. am!le of refraction of light wave ,

c) Refraction of o&n' wave (

1. *ound waves travel faster in warm air than in cool air.2. 3n a hot day 4

'he hot surface of the earth causes the layer of air near the surface tobe warmer. 'his causes sound waves to be refracted away from theearth.

3n a cool night 4'he sound waves travel slower in the cooler layer of air near thesurface of the earth than in the u!!er, warmer air. 0s a result, thewaves are refracted towards the earth.

/. 'his e!lains why sound can be heard over a longer distance on a coldnight com!ared with a hot day as illustrated as figure below.

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ACTIVITIES :

1. 0 water waves travelling from shallow area to dee! area with v ) 25 cms and /cms. 6ind the ratio of wavelength from shallow area to dee! area.# &1 4&2 $

2. raw a !attern of refraction of water waves from shallow area to dee! area.

/. When a light wave traveling in one medium crosses the boundary into a medium

with 7777777777777777777777 where it 777777777777777 is different.

. 8elocity is 7777777777777 at low density medium and velocity is 7777777777777 at high density medium.

5. *ound wave travel 777777777 in warm air than in cool air.

9. What ha!!en to sound wave on a hot day :

7777777777777777777777777777777777777777777777777777777777777777

7777777777777777777777777777777777777777777777777777777777777777

. What ha!!en to sound wave on a cool day :

7777777777777777777777777777777777777777777777777777777777777777

7777777777777777777777777777777777777777777777777777777777777777


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ASSESTMENT

(Objective questions )

1. Refraction of water wave is definedas

0. when a water wave travelling

from dee! area to shallow area.

>. waves s!read as they travel andwhen they encounter obstaclesor slits they bend around it and!ass into the region.

?. when a wave travelling in onemedium crosses the boundaryinto a medium with differentdensity where it velocity is

different.

2. Refraction of light wave is defined as

0. waves s!read as they travel andwhen they encounter obstacles or

slits they bend around it and !assinto the region.

>. when a wave travelling in onemedium crosses the boundary intoa medium with different densitywhere it velocity is different.

? when a wave travelling from dee!area to shallow area

/. ffect of refraction of waves are asbelow ece!t

0. velocity will change afterrefraction.

>. fre%uancy same before and afterrefraction.

?. wavelength same after refraction.

.wavelength will change afterrefraction.

. 0n audio signal generator !roducessound with constant s!eed. When thefre%uency of the sound increases, itswavelength ..

0. decreases

>. increases

?. remains constant

5. *ound waves travel 7777777 inwarm air than in cool air.

0. 8ery slow

>. *low

?. *ame

. 6aster

9. What ha!!en to sound wave on a hotday :

0. Remains constant.

>. ffect to human body.

?. *ound waves are refractedtowards the earth.

D. *ound waves to berefracted away from the earth.

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(Structure question)

1. ?om!lete the diagrams as below by drawing the wavefronts to show therefraction of water waves.

2. Water waves undergo refraction when moving from a dee! area to a shallowarea. @a"e a com!arison between incident waves and refracted waves interms of#a$ wavelength,

#b$ fre%uency,#c$ s!eed,#d$ direction of !ro!agation.

/. An figure above, a !lane wave with fre%uency BC and velocity < cms1

travelling from shallow area to dee! area. 6ind the wavelength in#a$ shallow area and#b$ dee! area.

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ANSWER EY.

*Activit+)

1. 5 4 9

2.

#/ D


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1.3 refraction of waves editted

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