Chapter 6 Waves (Student's Copy) 2014

8/13/2019 Chapter 6 Waves (Student's Copy) 2014

1/43

Physics Module Form 5

Prepared By : Mohd Syahmi Samsudin Chapter 6:Wave

6.1 Understanding Waves

1. Motion of Waves

A wave front is a line or plane on which the vibration of every points on it are in phaseand are at the.(same/different) position from the source of the water.

2. When we use a finertip to touch the surface of water repeatedly! ....(circular/plane)wavefronts are produced.

". #ypes of waves#here are 2 types of waves $%

(a) . (b) .

&. #ransverse wave(i). #ransverse wave is a wave in which the vibration of particles in the medium is

at .. (parallel/perpendicular) to the direction of propaation of the wave.

A ' .(crest / compression)

' ..(rarefaction /trouh)

(ii). *ample of transverse wave$ i. .. ii... iii..

+. ,onitudinal waves (i) A lonitudinal is a wave in which the vibration of particles in the medium is

.(parallel / proportional) to the direction of propaationof wave.

(ii) *ample of lonitudinal wave$..- ' ..(crest / compression)

' ..(rarefaction / trouh)

1

A A

-

-

CHAPTER 6: WAVE


2/43



Amplitude, Period and re!uen"# o$ a Wave

iure 0.2

1. uilibrium position is .

2.3ne complete oscillation of the pendulum occurs when the pendulum bob moves from............

". #he period! # of a vibratin system is ...&. reuency! f is

#he 4.5. unit is ..

$ %T

1 or $ %

t

n

+. 4troboscope is use to .. 4troboscope freuency ' number of slits * rotation freuency of stroboscope

or

0. Wave speed5f the wavelenth of the wave is ! the waves move forward a distance off* per second. #herefore! the speed of waves! v

v% $

2

A

6 A

6

reuency! f

#he number of complete oscillations

second.#he 4.5. unit is 7ert8 (78)

&uestion '

A child on a swin ma9es 2 complete swins in

" seconds. What is the freuency of theoscillation:

&uestion (

5n an e*periment ! ,im observes that a simplependulum completes " ascillations in &;.seconds. What is

the period of oscillation:#he freuency of oscillation:

&uestion '

A child on a swin ma9es 2 complete swins in

" seconds. What is the freuency of theoscillation:

&uestion (

5n an e*periment ! ,im observes that a simplependulum completes " ascillations in &;.seconds. What is

the period of oscillation:#he freuency of oscillation:

reuency! f#he number of complete oscillations second.#he 4.5. unit is 7ert8 (78) $ % 1 or $ %

T

$ % np


3/43



E)er"ise 6.1

iure 0.1

1. (a) #he wavelenth of the wave in the diaram above is iven by letter .

(b) #he amplitude of the wave in the diaram above is iven by letter

2. 5ndicate the interval which represents one full wavelenth.

iure 0.11

Answer$

"

* *


4/43



E)er"ise 6.11

1. 5n an e*periment ! ,im observes that a simple pendulum completes " oscillations in

1+. seconds. What is

(a) the freuency of oscillation: (b) the period of oscillation:

Anser: (a) f ' "/1+ ' 2 78 (b) # ' 1/f ' 1/2 ' .+ s

2.

6alculate the freuency of the iven wave above. Anser : T ! "s

f !T

1 #$

! %&'5 #$

". ased in the displacement%distance raph of a wave! find(a) the amplitude

(b) the wavelenth of the wave

Anser:(a) amplitude ! 5 cm

(*) Wavelen+th ! %&" cm

&

+

%+

2 &


5/43



&. A transverse wave is found to have a distance of & cm from a trouh to a crest! afreuency of 12 78! and a distance of + cm from a crest to the nearest trouh.


6/43



>. #he fiure shows a wavefront pattern in a ripple tan9 produced by a vibratin dipper atfreuency of + 78. What is the wave speed:

Anser:

f ! 5 #$ ! "&5,- ! .&5 cm/ ! f

! 0&5 cm s1.

;. A mechanical stroboscope has 12 slits and rotates at a freuency + 78. #he stroboscope is used to observe water waves. #he observer notes there are 0 successive briht bands at a distance 2 cm. 6alculate the speed of the water waves.

Anser: f ' n p ' 12 * +

' 0 78

?. #he fiure shows a loudspea9er produces a sound with a freuency " 78. 6alculate

(a) the wavelenth.(b) the speed of sound Anser:

(a) %&6 m

(*) / ! f

! -%% 2 %&5

! .5% m s1.

0

+

.- "m

2 cm (+)

' 2/+ ' & cm

= ' f ' 0 * &

' 2& cm s%1


7/43



1. A iven wave travels at a speed of 2 * 1+ms%1. 5f the freuency of the wave is 1 78! 6alculate the wavelenth Anser:

! v,f

!1

12 +

2

! '%% m

11. (a) aseon the fiure determine!

(i) the amplitude (ii) the wave lenth (b) What is the freuency of the sound if the speed of sound is "" ms%1. Anser:

(a) (i) ' cm

(ii) 5% cm

(*) f ! v ,

! --% , %&5

! 66% #$

amping

iure 0.12

>


8/43



1.


9/43



*ercise 0.2 6omplete the diaram below.

Re$le"tion o$ 7ater 7aves

1.4how the pattern of the reflection of the water waves

(b)

2. 4how the dar9 and briht pattern on the screen below.

(a)

(b)

?


10/43



' riht < '


11/43



Re$le"tion o$ 0igt Wave

1. When rays of liht stri9e any surface the rays are reflected ! unless the surface is blac9! when they are absorbed.2. A plane mirror is a flat smooth surface which reflects reularly most of the liht

fallin on it.

iure 0.2 1. #he characteristics of reflection of liht waves$

2. #he briht and dar9 bands of the wave pattern formed on the screen because thesurface of water acts as lenses. #he crest of water waves similar with .

(concave lens ,conve2 lens)and the trouh of water waves similar with (concave lens ,conve2 lens)&

E)er"ise 6.'1

#he diaram shows a sinle ray of liht bein directed at a plane mirror. What are theanles of incidence and reflection:(a) (b)

Anser:

i !r ! % -5 ! 55o

i ! r ! 0% o

2.

11

"+o


12/43



R e$le"tion o$ sound 7aves

1. #he sound waves is reflected by walls and ceilins of buildins! unborn baby or sea

bed.

iure 0.21

2. #he sound wave from the stopwatch e*perience a reflection after stri9in the smoothwall.#he anle of incidence! iis .(eual to /more than/less than) the anle ofreflection! r.

E)er"ise 6.''

1. #he diaram shows a student shoutin in front of a school buildin. 6alculate the timeta9en by the student to hear the echo of his voice.

C#he speed of sound in air is "& m s%1D

Answer$

12

e4ual to


13/43



2.

5f an echo is heard one second after the holler and reflects off canyon walls which are adistance of 1> meters away! then what is the speed of the wave:

Answer$

6.( A/A023/4 RERACT35/ 5 WAVE2

1. #he refraction of water waves occur when there is a

1. After refraction! the wave has the same . but a different.

1"

chan+e of direction of the propa+ation of avestravelin+ from a medium to another medium due

to a chan+e of speed&

's ! v 2 t

! ' (.0%) ! -"% m s1.

.

iure 0."


14/43



Re$ra"tion o$ Water Waves


15/43



3n each of the followin diaram! draw the refracted wave by the perspe*.

(a) (b)

(c) (d)

(e) (f)

2. A plane wave has a wavelenth of 2 cm and a velocity of ; cms%1as it moves over thesurface of shallow water. When the plane wave moves into an area of reater! depth! itsvelocity becomes 12 cms%1. What is the

a. wavelenthb. freuency

of the wave in the area of reater depth: Anser:

1+


16/43



Re$ra"tion o$ 7ater 7ave o$ te sea 7ater

iure 0."2

1. Why are the speed and wavelenth of waves in the middle of the sea almost uniform:

2. What do you thin9 would happen to the wave speed if the depth of water is increased:

...

". Why do the distances between the wavefronts decrease as the waves approach the beach:

&. Why is the water in the bay stationary compared to the water at the cape:

10

The depth of ater varies across the area of the *ay

The ener+y of the ater ave spreads to a ider area as compared to the re+ion near the capeThe amplitude of the ater ave near the *ay is lo and hence the ater at the *ay is

comparatively still


17/43



Re$ra"tion o$ 0igt Waves

iure 0.""1. When a ray propaates from one medium to an optically denser medium! the ray refracts

;;;;;;;(toards , aay from) the normal.

2. #he speed of liht ;;;;;&(decreases,increases)as it propaates in the lass bloc9!

causin it to alter the direction of propaation. Re$ra"tion o$ 2ound Waves

iure 0."& (a) iure 0."& (b)

1. 4ound waves travel faster in warm air than in .. (cold/hot) air.

2. 3n a hot day! the hot surface of the arth causes the layer of air near the surface to be (armer,cooler)

". #his causes sound waves to be . (reflected,refracted)away from the arth.

&. 3n a cool niht! the sound waves travel .(sloer,faster)in the cooler layer of airnear the surface of the arth than in the upper! warmer air. #he waves are refractedtowards the arth.7ence! sound can be heard over a loner distance on a cold ;;;&(ni+ht,day)comparedwith a hot day.

1>

cold

refracted

sloer

ni+ht

lass bloc9

normal

toards

decreases

air


18/43



6. A/A023/4 3RACT35/ 5 WAVE2

1.


19/43



2. 6omplete the diarams below by drawin the wavefronts to show the diffraction of waterwaves.

rom the diaram above!1. #he .(narrower/wider) the ap! the more the waves spread out.2. When the ap is much wider than the wavelenth of the waves! there is . (little/more) diffraction.

1?

(b) Wider ap F B(a) Garrow ap H B

(d) Garrow obstacle

(c)Wider obstacle

narroer


20/43



Diffraction of light waves

iure 0.&


21/43



iure 0.&2

21


22/43



1. A listener is reuested to stand on the other side of the corner of the wall so that the radiois beyond his vision.

2. #he listener is able to hear the sound of the radio althouh it is behind the wall. ". 5t is because the sound of the radio spreads around the corner of the wall due to diffraction

of sound.

1. 5nterference is the superposition of two waves from two coherent sources meet

2. #wo waves are in coherent if they are of the same .and !

". #here are two types of interference $

Prin"iple o$ superposition

1. #he principle of superposition states that

2. 6onstructive interferenceoccurs when

".


23/43



When the vertical displacemet of two waves are in the same direction as in iure 0.+(a) and (b)! (constructive/destructive) interference occurs.

(b)


24/43



E)er"ise 6.-

iure 0.+"

1. iure 0.+" shows the interference pattern of water by two coherent sources of waterwaves.

(i) At point A! two crest meet resultin in .. interference.(ii) At point ! two throuh meet resultin in ..interference.(iii) At point 6! a crest meet a trouh resultin in interference.

2.. 6omplete the table below.

efore superposition


25/43


26/43



6omplete the crossword pu88le.

1. #wo sources are said to be if they have the same freuency ofvibration and a 8ero or constant phase difference.

2. We can use a ripple tan9 to observe ..patterns of water waves.

". Antinodes are points where ..intaference occurs.

&. Godes are points where interference occurs.

+. Antinodal lines are lines Joinin

0. Godal lines are lines Joinin

20


27/43



3nte$eren"e o$ 0igt Waves

A ray of liht passes throuh the sinle slit and reaches the double%slit will ive riseto two coherent liht rays.

1. 5nterference occur when at least two coherent liht waves overlap or superpose

2. #he superposition of 2 rays produces$ (i) (ii)

". When constructive occurs there will be a (briht/dar9) frine When destructive occurs there will be a (briht/dar9) frine

2>


28/43



&. #he wavelenth of monochromatic liht can be found by the formula$

a ' .. * ' .

< ' .

E)er"ise 6.-1

1. 5n a Koun@s double slit e*periment! a liht of wavelenth 0"" nm passes throuh

two slit which are .+ mm apart. =ertical frines are observed on a screen placed& m from the slits.

(i) 6alculate the distance between two adJacent briht frines.(ii) What will happen to the distance between two adJacent briht frines if

a liht of shorter wavelenth is used:

Answer$(a) ! 6-- nm ! 6-- 2 .%1

a ! %&5 mm ! %&5 2 .%1- m7 ! " m

(b)

5f is smaller! * will also be smaller. #herefore ! the distance between twoadJacent briht frines of liht will smaller.

2;

is the distance *eteen the slitsis the distance *eteen the dou*le1slit and the screen

is the distance *eteen consecutive *ri+ht or dar< frin+es

1& mm


29/43



2. #he wavelenth of liht can be determined with a double%slit plate. #he diaramabove shows the pattern of interference frines obtained in a Koun@s double%slite*periment. #he separation distance of the two slit is .2 mm and the distancebetween the screen and the double%slit plate is &. m.6alculate the wavelenth of the liht used in the e*periment.

Answer$02 ! ." mm 2 ! ' mm ! ' 2 .%1-m

7 ! -&% m

3nte$eren"e o$ 2ound Waves

#he wavelenth of sound wave can be found by the formula$

a ' .. * ' . < ' .

2?

distance *eteen to loudspea


30/43



E)er"ise 6.-'

1. #wo loud spea9ers placed 2 m apart are connected to an audio sinal enerator that isadJusted to produce sound waves of freuency ++ 78. #he detection of loud and softsounds as a person moves alon a line is at &. m from the loudspea9ers.

6alculate the(a) wavelenth(b) speed

of the sound waves.

Answer$ (a)

(*)f ! 55% #$

/ ! f

! 55% 2 %&6

! --% m s1.

6.6 Anal#sing 2ound Waves

1. 4ound waves are lonitudinal waves which reuire a medium for its propaation.

2. #he loudness of the sound is depend to the

"


31/43



". #he pitch of the sound is depend to the .....................

&. cho is

Appli"ation o$ 2ound Waves

1. Eltrasonic waves with freuencies above 2 978 cannot be heard by human ear.2. #he ultrasonic ruler is used to measure the distance between itself and a taret.". #he depth of sea water can be calculated usin the formula $

2d ' v * t

E)er"ise 6.6*

"1

amplitude


32/43



2. When a wave reaches the (1) ..........from one medium to another medium! aportion of the wave underoes reflection while the other portion of the waveunderoes transmission across the boundary.

". #he (2). 4ound will be heard when the anle of incidence! 5 euals theanle of reflection! r

&. #herefore! we can say that sound waves obey the laws of (")..+. (&)..that are causes by multiple reflections from numerous reflectin

surfaces of a lare hall can create an impression that sound lasts for a lontime.

0. 5f the reflector is near to the sound source! the reflected sound will overlap theoriin sound. 5t will not be heard as a separate sound! but as a proloned oriinsound 9nown as (+)

2. 5n an e*pedition to determine the depth of a freshwater la9e usin an ultrasonicruler! a pulse of ultrasonic sound is enerated and travels to the bottom of the la9eand reflected by it. #he time ta9en by the pulse to travel to the bottom of the la9eand return to the ruler is ."+ s. 5f the speed of sound in freshwater is 1&;2 m s%1!calculate the depth of the la9e.

Answer$

"2


33/43



". ill in the blan9.

ield ApplicationMedicine Sound aves of hi+h ener+y are directed

to the


34/43



0.> Anal#sing Ele"tromagneti" Waves

1. #he electric and manetic field vibrate ..(perpendicular/parallel) toeach other and to the direction of propaation.

2. -roperties of electromanetic waves (i) (ii)

(iii) (iv)

". 4ources and applications of electromanetic waves in daily life

#ype of em wave 4ource Application

adio waves' 1%1% 1+m

=lectrical oscillatin+

circuit

(a) telecommunications

(*) *roadcastin+ : tv and radio

transmission

Microwave

' 1%"

L 1%1

m

>scillatin+ electrical

char+e in a microavetransmitter

(a) satellite transmissions

(*) radar(c) coom

The sun3 hot o*?ects3

li+ht *ul*s3 fluorescent

tu*es

(a) si+ht(*) photosynthesis in plants

(c) photo+raphy

Eltravioletradiation' 1%?L 1%>m

/ery hot o*?ects3 the sun3mercury vapor lamps

(a) identification of counterfeit notes

(*) production of vit17(c) Sentrilisation to destroy +erms

%ray' 1%11L 1%?m

21ray tu*es

(a) @adiotherapy

(*) 7etection of crac


35/43



E)er"ise 6.9*

1. #he diaram below shows the pattern of spectrum electromanetic. 5n the bo*es provided! write the names of the parts iven .

2. #able 0.> shows electromanetic waves -! ! and 4 and their uses

lectromanetic waves Eses- emote control

adar system -hotoraph4 Oill cancerous cells

#able 0.>

5dentify -! ! and 4

Answer$ P ! 8nfra1red rays ! Microaves

@ ! /isi*le li+ht

S ! amma rays

"+

amma

ray

D1ray 9ltra

/iolet

/isi*le

li+ht

infrared microave radioave

7avelengt

$re!uen"#

adiowave microwave amma ray *%ray visible ray infra%red ray ultraviolet ray


36/43



Rein$or"ement Capter 6

Part A : 5;e"tive &uestions

1. 6alculate the freuency of the iven wave above

A. ; 78.. 1/; 786. & 78.


37/43



+. Wave lenth of iven wave does G3# depend on.

A. velocity.. reuency6. Amplitude

. A iven wave travels at a speed of & * 1+ms%1. 5f the freuency of the wave is 1 78!calculate the wavelenth

A. 1 m. 2 m6. " m


38/43



Part 8: 2tru"tured &uestions

iure 1

1. iure 1 shows the use of sonar euipment to measure the depth of the sea.(a) 4tate the phenomenon of sound wave applied in sonar euipment.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

C1 mar9D(b) 4ound waves with freuency of 0. * 1+ 78 are used to determine the depth ofthe sea. Cspeed of sound in sea water ' 1+ m s%1D

(i) What is the wavelenth of the sound wave in sea water:

C2 mar9sD(ii) 5f the time interval between the instant the sound wave is sent to the

instant the echo is received is 1.+ s! what is the depth of the sea

C2 mar9sD

2.

iure 2

A pin pon ball is held with a strin and placed near a loudspea9er as shownin iure 2#he loudspea9er emits a low freuency sound and the pin%pon ball seems tovibrate to it.

";

@eflection


39/43



(a) *plain how the sound from the loudspea9er produces vibration on the pinpon ball.The vi*ration of the loudspea


40/43



&. Kou are assined to investiate the properties of waves that could be used inbroadcastin and communication. #able below shows the properties of si* typesof waves -! ! ! 4 # and E.

Wave #ype of wave Material medium

for propaation

4peed of wave -enetratin power

- #ransverse Got reuired " * 1;ms %1 -enetrates matter #ransverse Got reuired " * 1;ms %1 Absorbed by lass #ransverse Got reuired " * 1;ms %1 efracted by lass4 #ransverse Got reuired " * 1;ms %1 Medium# ,onitudinal euired "" ms %1 Wea9E ,onitudinal euired 1 ms %1 Wea9

ased on the table! select the most suitable wave that could be used inbroadcastin and communication and ive your reasons.

C1 mar9sD

Anser:

5& iure +.1 shows the arranement of the apparatus tor an e*periment to study awave phenomenon.

iure +.1

iure +.1 shows the briht and dar9 bands of the wave pattern formed on the

&


41/43



white piece of paper produced by the vibration of two spherical dippers on thewater surface.

iure 1.2iure 1." iure +.2iure +."

(ii) 3bserve iures +.2 and +.". 6ompare the wave patterns produced by the spherical dippers.

4tate the relationship between the distance of the two coherent of twoconsecutive node or antinode lines. C+ mar9sD

Anser:

&1


42/43



Part C: Essa#

1. iure 0. shows the arranement of the apparatus for an e*periment to study a wavephenomenon.

iure0.

iure 0.1 shows the briht and dar9 bands of the waves pattern formed on the whitepaper when plane waves passes throuh the narrow and wide aps.

Garrow ap Wide ap iure 0.1(a) iure 0.1(b)

(a) Game the wave phenomenon shown in fiure 0.2.

7iffraction C1 mar9D

(b) (i) *plain how the dar9 and liht bands are formed on the white paper. C& mar9sD

&2

Q iure /6rests act as aconve* lens

Q Fi+ure , =very crestsill conver+e the li+ht3 *ri+ht

frin+es are formed

Q Fi+ure , =very trou+hs illdiver+e the li+ht3 dar< frin+es are

formed


43/43



(ii) 3bserve iure 0.2(a) and (b). 6ompare the waves patterns and the wavelenth ofthe waves before and after they pass throuh the aps.

elate the si8e of the aps! the waves patterns and the wavelenths to deduce arelevant physics concept.

C+ mar9sDa& 8n fi+ure -&.(a)3 si$e of the avelen+th is the same as si$e of the +ap ,, 8n fi+ure

-&.(*)3 si$e of the +ap is ider than*&

The narroer the +ap the +reater the spreadin+ of the ave

(c) iure 0." shows the seashore of a fishin villae.

Chapter 6 Waves (Student's Copy) 2014

Documents

Transcript of Chapter 6 Waves (Student's Copy) 2014