MODUL F5 (WAVES).doc

8/10/2019 MODUL F5 (WAVES).doc

1/33

Physics Module Form 5 Students Copy 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)

IZZAT 1

A A

-

-

CHAPTER 6: WAVE


2/33


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% $

IZZAT 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


3/33


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$

IZZAT "

* *


4/33


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

IZZAT &

+

%+

2 &


5/33


&. 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.


6/33


>. #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.

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

IZZAT 0

2 cm (+)

' 2/+ ' & cm = ' f ' 0 * &

' 2& cm s%1


7/33


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

IZZAT >


8/33


1.


9/33


*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.

' riht < '


10/33


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.

IZZAT 1

"+o


11/33


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.''

IZZAT 11

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$

e4ual to


12/33


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.

IZZAT 12

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."


13/33


Re$ra"tion o$ Water Waves


14/33


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:

IZZAT 1&

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


15/33


Re$ra"tion o$ 0igt Waves

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

8888888(toards , aay from) the normal.

2. #he speed of liht 88888&(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 refracted

towards the arth.7ence! sound can be heard over a loner distance on a cold 888&(ni+ht,day)comparedwith a hot day.

IZZAT 1+

cold

armer

refracted

sloer

ni+ht

lass bloc9

normal

toards

decreases

air


16/33


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

1.


17/33


18/33


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

".


19/33


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

(b)


20/33


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


21/33


". 6ateori8e each labeled position as bein a position where either constructive ordestructive interference occurs.

(a) 6onstructive interference$. (b)


22/33


3nte$eren"e o$ 0igt Waves

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

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

a ' .. * ' . < ' .

IZZAT 22

is the distance *eteen the slits

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

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


23/33


E)er"ise 6.-1

1. 5n a Joun@s double slit e*periment! a liht of wavelenth 0"" nm passes throuhtwo slit which are .+ mm apart. =ertical frines are observed on a screen placed& m from the slits.

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

a liht of shorter wavelenth is used:

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

a ! %&5 mm ! %&5 2 .%1- m9 ! " m

(b)

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

2. #he wavelenth of liht can be determined with a double%slit plate. #he diaramabove shows the pattern of interference frines obtained in a Joun@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

9 ! -&% m

IZZAT 2"

1& mm

a ! %&' mm ! ' 2 .%1"m

!

! . 2 .%10 m


24/33


3nte$eren"e o$ 2ound Waves

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

a ' .. * ' . < ' .

E)er"ise 6.-'

1. #wo loud spea9ers placed 2 m apart are connected to an audio sinal enerator that is

adIusted 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.

IZZAT 2&

distance *eteen to loudspeaers

distance *eteen to consecutive loud placesperpendicular distance *eteen the speaers and

the loud


25/33


6.6 Anal#sing 2ound Waves

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

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

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

&. cho is

Appli"ation o$ 2ound Waves

1. Kltrasonic 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. 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 thela9e and reflected by it. #he time ta9en by the pulse to travel to the bottom of thela9e and 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$

IZZAT 2+

a phenomenon hen a sound ave has *een reflected off a

surface 3 and is heard after the ori+inal sound&

amplitude

fre4uency


26/33


2. ill in the blan9.

6.9 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

m

The sun3 hot o*=ects3

li+ht *ul*s3 fluorescent

tu*es

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

(c) photo+raphy

Kltraviolet

radiation' 1%?L 1%>m

/ery hot o*=ects3 the sun3mercury vapor lamps

(a) identification of counterfeit notes

(*) production of vit19(c) Sentrilisation to destroy +erms

%ray' 1%11L 1%?m

21ray tu*es

(a) >adiotherapy

(*) 9etection of cracs in *uildin+structures

Namma rays' 1%1&L 1%1m >adioactive su*tances

(a) Cancer treatment(*) Sterilisation of e4uipment

(c) Pest control in a+riculture

IZZAT 20

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

to the idney stones to destroy them in thecavity of the idney&

5ndustry Sound aves of hi+h ener+y are directedto the idney stones to destroy them in thecavity of the idney&

Transverse aves

9o not re4uire a medium to propa+ate and can travel in a vacuumThe aves travel at the speed of li+ht3 c ! - 2 .%?ms1.

@nder+o the same aves phenomenon : reflection3 refraction3 diffraction andinterference&

perpendicular


27/33


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 Kses- emote control

adar system -hotoraph4 Oill cancerous cells

#able 0.>

5dentify -! ! and 4

Answer$ P ! nfra1red rays B ! Microaves

> ! /isi*le li+ht

S ! amma rays

IZZAT 2>

amma

ray

D1ray @ltra

/iolet

/isi*le

li+ht

infrared microave radioave

7avelengt

$re!uen"#

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


28/33


Rein$or"ement Capter 6

Part A : 5;e"tive &uestions

1. 6alculate the freuency of the iven wave above

A. ; 78.. 1/; 78

6. & 78.


29/33


30/33


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.

888888&

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.

IZZAT "

>eflection


31/33


(a) *plain how the sound from the loudspea9er produces vibration on the pinpon ball.The vi*ration of the loudspeaer moves the air molecules around it&The sound ave produced *y the loudspeaer transfers ener+y to the pin+

pon+ *all and causes it to move

(b) What will happen to the vibration of the pin pon ball if the loudness emits (i) a louder sound: The pin+ pon+ *all vi*rates ith +reater amplitude

(ii) a sound with a hiher pitch: The pin+ pon+ *all vi*rates ith hi+her fre4uency&

(c) 5f the freuency of the sound is + 78! calculate the wavelenth of the soundproduced. CAssume the speed of the sound in air in "+ ms%1D

2. (a) iure " shows two sets of ripple tan9s used to study diffraction of waves.

iure ".1 iure ".2

(i) What is meant by the diffraction of waves.9iffraction is the spreadin+ out of aves hen they move throu+h a +apor around an o*stacle

(ii) Which of the two sets will show a bier effect of diffraction. *plain

your answer.The set shon in Fi+ure "&. ill sho a *i++er effect of diffraction& This is

*ecause the narroer the +ap3 the more the aves spread out&

(iii) edraw and complete iure ".1 and iure ".2 to show the between thetwo diffraction patterns.

(iv) 4tate the characteristic to the diffracted waves in terms of waves in termsof wavelenth! freuency! speed and amplitude compared to the incidentwaves.

(a) Wavelen+th remains unchan+ed(*) Fre4uency remains unchan+ed

(c) Speed remains unchan+ed

(d) Amplitude *ecomes smaller compared to the incident aves

IZZAT "1


32/33


Part C: Essa#

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

iure ".

iure ".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.

Farrow ap Wide ap iure ".1(a) iure ".1(b)

(a) Fame the wave phenomenon shown in fiure 1.2.

9iffraction C1 mar9D

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

IZZAT "2

Q iure /6rests act as a

conve* 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 areformed


33/33


(ii) 3bserve iure ".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 a

relevant physics concept. C+ mar9sD

a& n fi+ure -&.(a)3 si$e of the avelen+th is the same as si$e of the +ap ,, n fi+ure-&.(*)3 si$e of the +ap is ider than

*&

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

(c) iure 1." shows the seashore of a fishin villae.

MODUL F5 (WAVES).doc

Documents

Transcript of MODUL F5 (WAVES).doc