01•Ch 1(F5 wave)

Longman Project! Overhead Transparencies Physics Form

5

Pearson Malaysia Sdn.Bhd. 2007

CHAPTER

111

1

Waves

1.1 Understanding Waves

Waves transferenergy

load

motor

(a) Vibration of a plastic bob on water

(b) Vibration of a loaded spring

(c) Vibration of a tuning fork(d) Oscillation of a simple

pendulum

Waves

Examples of vibration

Sound wave


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CHAPTER

111

2

Waves


Displacement Graphs of Waves

x/cm

T

T

- a - a

a

-xo

xo

T

t/sO

x/cm

a

-xo

xo

O distance/cm

Amplitude, a= maximum displacement, Xo

Amplitude, a= maximum displacement, Xo

Period, T= time taken for one complete

wave

Wave length, = distance travelled by a

complete wave

Frequency, f= number of complete waves

in one second

Velocity of wave, v

v = f = T

Displacement time Displacement distance


5


CHAPTER

111

3

Waves


Type of Waves

compression

Direction of wave

Direction of vibration

C CR

rarefaction

Direction ofvibration

Direction ofpropagation

Direction ofvibration

Direction of wave


Direction ofpropagation


Direction of wave


Direction of wave

Direction of wave Direction of wave

Longitudinal wave

Water waves, light waves,electromagnetic waves, etc.

Sound waves, impulses along aslinky spring, etc.

Transverse wave

Directions of vibrating particles

Propagation of waves

Examples


5


CHAPTER

111

4

Waves


X

X

X

y

y

y

turned180o

turned90o

polarised

polarised

no waveis formed

polarised wavesingle slit

Transverse wave

cross-slit

Xy

polaroidTransverse wave

Bright image

Less brightimage polaroidsunglasses

Too dark to see

Polarisation of Transverse Wave


5


CHAPTER

111

5

Waves


Same frequency

Forcingagent

Forcedobject

Forcedvibration ofmaximumamplitude

Resonance

transferingenergy

Experiment to show resonance

A B C D EX y

X yA B C D E

Pendulums E and B havethe same naturalfrequency.

E vibrates with highenergy/amplitude.

Q

Q E loses energy to A, B, C

and D but B gains moreenergy.

B vibrates with highamplitude.B vibrates in resonance.

c

Q

weight

y

E

DC

B

A

X

Resonance


5


CHAPTER

111

6

Waves


Without damping With damping

displacement/cm

t/s

displacement/cm

t/s

Compare

Constant Amplitude (energy) Decreasing

Constantperiod, T

frequency, fspeed, v

Constant

External damping Internal damping

Work done againstexternal force

Work done by vibratingatoms or molecules

Damping Oscillations

Loss of energy in damped oscillations

white paper

lamp

stroboscope

transparent tray

sponge

motor

drainhose

spherical bob

wooden barwater


5


CHAPTER

111

7

Waves

1.2 Analysing Reflection of Waves

Proper adjustments

Constant water depth

Sponge

Speed of motor

Height of lamp

Stroboscope

to ensure constant speed/wavelength

to reduce reflection of water waves

to adjust the speed of water waves

for illumination and focussing of image

to freeze the wave pattern

Ripple Tank

plane wave circular wave


5


CHAPTER

111

8

Waves


to ensure constant speed/wavelength

to reduce reflection of water waves

to adjust the speed of water waves

for illumination and focussing of image

to freeze the wave pattern

1 2v1 v2 v1=


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CHAPTER

111

9

Waves


Formation of Light Fringes of Water Ripple

2

waterripples

whitepaper

planes of light

acting as convex lens

Bright Bright Bright DarkDark

B B BD D

Bright fringes (image)

motor speed q f1q 1p motor speed p f2 p 2q

speed of wave isconstant

1 2v1 v2 v1=

Effect of Motor Speed

N (normal) N (normal)

incident waves i

reflected waves

reflected wavesr

reflected waves

i = r


5


CHAPTER

111

10

Waves


plane wave circular wave

plane reflector

concavereflector

convexreflector

Reflection of waves

N N

N N N N

F


5


CHAPTER

111

11

Waves


N N

N N

F

N N

reflected waves

N (normal) N (normal)

incident waves i

reflected waves

reflected wavesr

reflected waves

reflected waves

I Image

i = r


5


CHAPTER

111

12

Waves

1.3 Analysing Refraction of Waves

Examples of refraction

Special case

wavelength is

speed v is also

direction of waves

Refraction of Waves

deep water

1

shallow water Deep

watershallow water

deep water

deep water

deep water

deep water

shallow water

shallow water

shallow water

v1

N

N

N

N

deepwater

deepwatershallow

water shallowwater

deepwater

deepwater

shallowwater


5


CHAPTER

111

13

Waves


deep water

12

v2

shallow water Deep

water

deep water

deep water

deep water

deep watershallow water

shallow water

v1

N

N

N

N

wavelength is decreased

speed v is also decreased

direction of waves does notchange : No refraction

deepwater

deepwatershallow

water shallowwater

deepwater

deepwater

shallowwater

F


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CHAPTER

111

14

Waves


Refraction of Water Waves Near a Beach

A B C D

R

E F G

P

Q

X (cape)

Y (sea bay)

Depth of water Movement of water Amplitude ConditionPosition

P

Q

R

A B C D

R

E F G

P

Q

X (cape)

Y (Sea bay)


5


CHAPTER

111

15

Waves


Decreasing

Shallow

Deep

Converging at P

Spreading out

Straight

Highest

Low

High

Very rough

Calm

Rough


5


CHAPTER

111

16

Waves


Effect of Water Depth on Waves

motor switched on(vibrating) A B C water

waves

glass(transparent)

water

Position

A

B

C

Depth of water

3.0 cm

2.0 cm

1.0 cm

f

same

same

same

long

shorter

shortest

v

fast

slower

slowest


5


CHAPTER

111

17

Waves


same

same

same

long

shorter

shortest

fast

slower

slowest


5


CHAPTER

111

18

Waves

1.4 Analysing Interference of Waves

Interference of Waves

Resultant amplitude

Resultantamplitude

a a

Water waves

a a2a

-2a

-a-acork a

-a a = 0cork cork

+

2a

a

a a

+-a

a = 0

Constructive interference Destructive interference

Standing waves

S1

S2

a

troughcrest AN

AN

AN

N

N

x

n = 0

n = 1

n = 1

D

Antinodal line

Nodal line

Constructive interference

Destructive interference


5


CHAPTER

111

19

Waves


Vibrating

Interference of Water Waves

Production of coherent waves

Wave pattern of interference

Coherent waves

same frequency same amplitude same phase or constant phase

difference

= axD


5


CHAPTER

111

20

Waves


Formula is where = wavelengtha = distance between two slitsx = distance between fringes

(n = 0 and n = 1)D = distance between the slits

and the screen

= axD

Youngs Double-Slit Experiment

colour filter

4 metres

double slit

screen

double slit

monochromatic light source

a

S1

S2

AN

AN

D

n = 2

n = 2

n = 1

n = 1

n = 0x

bright fringesscreen

dark fringes


5


CHAPTER

111

21

Waves


(a) Single source small wavelength

(b) Single source bigger wavelength

Fringe patterns

S1

S1


5


CHAPTER

111

22

Waves


(c) Double sources small wavelength

(d) Double sources bigger wavelength

Fringe patterns

S2

S2


5


CHAPTER

111

23

Waves

1.5 Analysing Diffraction of Waves

Pattern of Waves By Diffraction

Short obstacle Long obstacle

Narrow slit Wide slit

Small Big

The bigger the wavelength, the better the diffraction

1 Straight obstacle

2 Effect of slit size ( stays the same)

3 Effect of wavelength (slit size stays the same)

Interference occurs nearer to the shorter obstacle

Diffraction angle 1 > 2 Narrow slit produces better diffraction


5


CHAPTER

111

24

Waves


interferenceinterference

12


5


CHAPTER

111

25

Waves


n = 2n = 1

n = 0n = 1

n = 2

screen

single slit

Monochromatic light source

For fringe n = o, : broadest and brightest As nq, width/brightness of fringe p

Diffraction of Light

single slit pin hole

Diffractioninstrument

Fringe patterns

n = 3 n = 2 n = 1 n = 0 n = 1 n = 2 n = 3

bright fringes

dark fringes

Characteristics


5


CHAPTER

111

26

Waves


lamp set cylindrical

convex lens

bright fringes

XDiffraction grating3 000 lines cm1

D

x

Formula is n = order of diffraction = wavelength of lightd = distance between two slits in

a grating = angle of diffractionN = density of lines/slits

n = d sin

d = 1N

Monochromatic source White light source

Diffraction With Diffraction Grating

Fringe patterns

R R RV V V

spectrum of white light

white light

CRO

stopwatch microphone

60 510

15

20253035

40

45

5055

CRO

CO2microphone

Reflection


5


CHAPTER

111

27

Waves

1.6 Analysing Sound Waves

Longitudinal wave Requires a medium for

transmission

Properties

Original sound

Amplitude,aincreased

Frequency, fincreased

Higher pitchHigher loudness

radio

Diffraction

Loud

weak

Loudweak

Loud

Interference

Sound Waves

PhenomenaRefraction


5


CHAPTER

111

28

Waves


transmitter

waterd

detector

fish

in out

probe

ultrasonic

foetus

1 Using sonar to detect a school of fish or to determine the depth of water

2 For diagnosis of the human foetus

Ultrasonic used is safe Size of foetus can be estimated Picture taken is not very clear

Some Uses of Sound Waves

Depth of water

d = v ( )

where v = velocity of ultrasonic in watert = to and fro time

t2

microphone

Audio wave Radio wave

low amplitude

high amplitude

carrier wave

carrier wave

lowerfrequency

higher frequency

AM modulator

Radio frequency generator

Amplifier Amplifier

FM modulator

AM waveform FM waveform


5


CHAPTER

111

29

Waves


Amplitude modulation (AM) Frequency modulation (FM)

Amplitude of radio wave ismodulated

Frequency of audio wave andradio wave is not changed

Subjected to loss andinterference

AM

Amplitude of radio wave isconstant

Frequency of radio wave ismodulated

Minimum loss Minimum interference

FM

CHARACTERISTICS

AM and FM Waves


5


CHAPTER

111

30

Waves


Radio wave

Audio wave Transmitter

Amplifier

Radio frequency generator

Modulator

Amplifier

Sateliteionosphere

Relay-station

Radio Localtransmitter

Satelitestation

TV Long-rangetransmitter

Radio Waves (AM/FM) Transmitter

Mode of Transmission


5


CHAPTER

111

31

Waves


Simple Receiver For Radio Wave

Block Diagram

Circuit Diagram

}

Functions

To receive all types of radio signals

To tune the receivers frequency In resonance with received frequency Amplitude of wave received is increased

To separate the audio frequency from the radio frequency

To filter and earth the radio frequency

To amplify the audio frequency

To convert audio signal into sound

Components

A : aerial

I : inductorC1 : variable

capasitor

D : diode

C : capacitor

T : transistor

L : loudspeaker

aerial

Loud speaker

AmplifierFilter for radio frequency

DemodulatorTuner

A

C1I

D

C

T

L

B

Earthed


5


CHAPTER

111

32

Waves

1.7 Analysing Electromagnetic Waves

Electromagnetic Waves

vertical electrical field

90o

horizontal magnetic field

Frequencyf/Hz

1023 1022 1021 1020 1019 1018 1017 1016 1015 1014 1013 1012 1011 1010 109 108 107 106 105

1014 1013 1012 1011 1010 109 108 107 106 105 104 103 102 101 1 101 102 103 104

Wavelength

Frequencyf/ Hz

Radio waves

Xray Visible light Microwaves

UHF VHF SW MW LW

Gamma raysUltraviolet rays

Infrared rays

SW MW LW

UHF VHF

/ m

Gammarays

Ultraviolet

Visiblelight

Micro-waves

RadiowavesX-ray Infrared

Electromagnetic Waves Spectrum

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01•Ch 1(F5 wave)

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