Lesson 3-F5 Physics

8/18/2019 Lesson 3-F5 Physics

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Name : Teacher: Cheng Wui Leap

Subject : SPM Physics Class : F5 Physics

Chapter

:

Waves Lesson No :

!ate : "#$#$%

Topic : $& 'nalysing (e)raction o) Waves Time : "&**pm+,&**pm

Exercise

$& -.*#SPM/*50' tilte1 basin contains 2ater& Water is 1rippe1 at a constant rate into the

basin as sho2n in the 1iagram belo2&

Which pattern o) the 2ave)ronts 2ill be observe1 in the basin3

"& -."#SPM/*%0!iagram $4 sho2s a ripple tan 2ith a sloping base an1 a vibrator being vibrate1&

Which o) the )ollo2ing 2ave patterns can be seen on the screen3

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& -."#SPM/*60!iagram "* sho2s 2ater 2aves propagating in an area o) 1i))erent 1epths&

&

Which o) the )ollo2ing 1iagrams sho2s the propagation o) the 2aves correctly3

,& -.$#SPM/*40!iagram $6 sho2s 2ater 2aves propagating through a perspe7 bloc in a ripple

tan&

Which 2ave pattern is observe1 2hen the 2aves pass through the perspe7 bloc3

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5& -.%#P"#SPM/*40!iagram %&$ sho2s the si1e vie2 o) t2o ripple tans& When the motors are

s2itche1 on8 2ater 2aves 2ith the same )re9uency are pro1uce1&

!iagram %&" sho2s the 2aves )orme1 on the screens&

a; What is the meaning o) )re9uency3 -$ mar0

b;


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a ?7plain 2hy the 2ave )ront o) sea 2ater 2ill )ollo2 the shape o) the shore 2hen it

approaches the shore& - mars0

?7ercise

$& !iagram $ sho2s the ripples o) the 2ater 2ave moving )rom region L to region M& The time taen )or

the 2ave to travel )rom region L to region& M is *&@ secon1s&

Calculate

a; the )re9uency o) the 2ater 2ave8&

b; the ratio o) the spee1 o) 2ater 2ave in region L to that in region M&

"& ' plane 2ave travels )rom shallo2 2ater region to 1eep 2ater region& An the shallo2 2aterregion8 the spee1 o) the 2ave is "6 cms+$ 2hereas in the 1eep 2ater region8 the spee1 o) 2ater becomes %

cms+$& A) the 2avelength o) the 2ave in shallo2 2ater is cm8 2hat is the 2avelength o) the 2ave in 1eep

2ater3

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& ' plane 2ave is travelling )rom 1eep 2ater region to shallo2 2ater region& An the 1eep 2ater region8 the

spee1 o) the 2ave is %* cm s +$ an1 its 2avelength is 5 cm&

a; What is the )re9uency o) the 2ater 2ave3

b; A) the 2avelength o) the 2ave in the shallo2 2ater region is , cm8 2hat is the spee1 o) 2ater 2ave inthe shallo2 2ater region3

,& When an electromagnetic 2ave o) %&5 7 $*$, B travels )rom air to a 1enser me1ium8 its 2avelength

changes )rom ,&% = $*+6 m to ,&* $*+6 m& What is the spee1 o) the electromagnetic 2ave in the 1enser

me1ium3

5& !iagram " sho2s a set o) plane ripples being re)racte1 2hen it travels )rom 1eep 2ater region to shallo2

2ater region&

a; Calculate the ratio o) the spee1 o) 2ater 2ave in 1eep 2ater to that in shallo2 2ater&

b; A) the spee1 o) 2ater 2ave in shallo2 2ater is @&* cm s+$8 2hat is the )re9uency o) the 2ater 2ave3

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Exercise

$&

First situation

The oscilloscope 1isplay sho2s an increase in the amplitu1e o) the 2ave 2hen a balloon )ille1 2ith

carbon 1io7i1e is place1 bet2een the lou1speaer an1 the microphone as sho2n in Figure a;&

Second situation

The 2ater 2aves travel to2ar1s a conve7 shape1 region o) shallo2 2ater& The pattern o) the 2ater

2aves a)ter passing through the region o) shallo2 2ater is sho2n in Figure b;&&

a; i; State one similarity an1 one 1i))erence bet2een a soun1 2ave an1 a 2ater

2ave& -" mars0

ii; Stu1y Figures a; an1 b;& State in )ull the characteristics o) both situations an1 relate

the characteristics to a phenomenon& What is this phenomenon calle13 -% mars0

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b; Water 2aves get closer together as they approach the e1ge o) a pon1&

i; ?7plain this observation&

ii; With the use o) suitable apparatus8 e7plain ho2 you 2oul1 veri)y that the )re9uency o) the 2ater2ave is constant throughout its propagation on the sur)ace o) the pon1&

c; An 1aily li)e 2e )in1 that soun1s can be hear1 more clearly at night than in the 1ay& Dive an

e7planation )or this& State t2o )actors that a))ect the spee1 o) soun1 in a gas& -5 mars0

1.4 DIFFRACTION OF WAVES

$& What is 1i))raction o) 2aves3

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!i))raction o) 2aves is a phenomenon in 2hich 2aves spread out as they pass through a gap or

roun1 a small obstacle&

"& What are Characteristics o) 1i))racte1 2aves3

$& Fre9uency8 2avelength an1 spee1 o) 2aves do not chane&"& Changes in the direction o) propagation an1 the pattern o) the 2aves&

& The amplitu1e o) the 1i))raction 2ave 1ecreases so its energy decrease&

& What are the )actors that in)luence the e))ect o) 1i))raction3

The e))ect o) 1i))raction is obvious i):

$& the sie o) the gap or obstacle is s!a"" enouh

"& the 2avelength is "are enough&

The e))ect o) 1i))raction is o#$ious i) the shape o) the 1i))racte1 2aves more sprea1 out or more

circu"ar

Di%%raction o% sound

Soun1 1i))racting aroun1 corners so a""o&in us to hear others 2ho are speaing to us )rom a1jacent rooms&

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Di%%raction o% "iht

Light is 1i))racte1 i) it passes through a narro& slit comparable in sie to its 2avelength&

Bo2ever8 the e))ect is not obvious as the sie o) the slit increases& This is because the 2avelengths o) light

are $er' short&

$& We can hear the soun1 o) a ra1io place1 nearby a corner o) a 2all but 2e cannot see the ra1io&

Why3

Soun1 2aves are !ore easi"' 1i))racte1 in comparison to light 2aves because the 2avelength o)

soun1 2aves is !uch "oner than the 2avelength o) light 2aves&

Di%%raction o% &ater Proce1ure

$& ' ripple tan is )ille1 2ith 2ater an1 set up as sho2n&

"& S2itch on the po2er pac&

& Ese a barrier to bloc the inci1ent straight 2ater 2aves&


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O#ser$ation

a; Wi1e gap

The 2aves are ben1 only at the e1ges a)ter passing through the gap&

The e))ect o) 1i))raction is not obvious

b; Narro2 gap

The 2aves are circular an1 appear to originate1 )rom the small gap& The e))ect o) 1i))raction is obvious

a; Straight 2ater 2ave propagate to2ar1s an obstacle&

Conc"usion

's the sie o) the gap or obstacle is s!a""er 8 the e))ect o) 1i))raction becomes o#$ious.

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Exercise

$& -SPM/*@#P$#.$0!iagram $@ sho2s 2ater 2aves passing a bloc o) roc in a river&

&

Which phenomenon e7plains the propagation o) 2aves at =3

' (e)lection (e)raction

C !i))raction ! Anter)erence

"& -SPM/$*#P$#.*0!iagram ", sho2s 2ater 2aves passing through a gap&

Which phenomenon e7plains the propagation o) the 2aves3

' (e)lection (e)raction C !i))raction ! Anter)erence

(. The e))ects o) 1i))raction are clearly visible i) the 2i1th o) the gap is s!a ""er than &a$e"enth.

,& When the 2i1th o) the gap or sie o) the obstacle increases8 the e))ect o) 1i))raction becomes

noticea#"e "ess&

5& When the 2i1th o) an aperture is small or approaches the 1imension o) the 2avelength o) the 2ater2ave8 the pattern o) the 1i))racte1 2aves appears lie circu"ar 2aves&

%& The )igure sho2s the construction o) a 2all at the sea )ront o) a port to protect the port )rom being

hit by large 2aves&

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!ra2 the pattern o) the 2aves a)ter passing through the opening bet2een the 2alls& Bo2 1oes the

2all protect the port3

6& -SPM/*5#P"##.$*0Figure $*&$ sho2s the arrangement o) the apparatus )or an e7periment to stu1y

a 2ave phenomenon&

Figure $*&" sho2s the bright an1 1ar ban1s o) the 2ave pattern )orme1 on the screen 2hen plane

2aves pass through narro2 an1 2ipe gaps&

a; i; ?7plain ho2 the 1ar an1 light ban1s are )orme1 on the screen& -, mars0

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ii;


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i; the 1esign an1 structure o) the retaining 2all8

ii; the location o) the ne2 jetty8

iii; the sie or energy o) the 2aves&

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Lesson 3-F5 Physics

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