REFRACTION of light LAW OF REFRACTION Refractive Index (n)

incident normal
The incident ray, refracted ray & normal
ray i
1 = 3 =
1 at the point of incidence
all lie in the ________ plane
r
refracted For two given media, the ratio of
2 = 4 =
ray 2 sin i
is a constant
Phenomena when light travel from sin r
one medium to another medium of a.k.a

different optical __________ & Snell's Law 3 Type of refraction of light

For a light ray that passes from one Light travel Less Dense Denser Denser Less dense Less dense Denser
experiences a change in ________
transparent medium into another medium from medium medium medium medium medium medium
the ratio of sine of incidence angle E.g
Speed
to the sine of angle of refraction
of light
Ray travel
is a constant
perpendicular
Ray air glass air/glass
Refractive
sin i glass air glass/air
n =
sin r
index
Refraction index refer diagrams
Example
to the ray travelling from
medium 1 medium 2 N N
i1 i2
(vacuum/air) (glass/water) TOTAL INTERNAL REFLECTION
CONDITION
Refractive Speed of r2
Material -1 r1
Index (n) light (ms ) The light ray must travel from an optically
8
Air 1.00 3.0 x 10 1 ________ _________
= = =
8 medium medium
Water 1.33 2.3 x 10
The angle of incidence must be
2
Glass 1.50 2.0 x 108 ________ that the critical angle. ( i > c)
N N
Diamond 2.42 1.2 x 108 To find critical angle
medium 1 medium 1
medium 2 medium 2
=
sin i
=
sin r air
=
medium
n12 = n21 =
Real depth (D)
= =
Apparent depth (d)
n12
=
Speed of light in vacuum/air (c) Is it
=
Speed of light in medium (v) = E.g = ±45 days
to exam????
CRITICAL?
1 A ray of light travel from air to water 5 A coin rests at the bottom of a container 8 Calculate the critical angle for
o
at angle of incidence of 30 of coffee when viewed from above, (i) glass, n = 1.5 (ii) water, n = 1.33
Given refractive index for water is 1.33 the coin appears to be raised up to
Calculate one-third of the liquid. What is the
(a) The angle of refraction, r refractive index of the liquid?

9 Calculate the refraction index for a medium a

(i) critical angle of 60o (ii) critical angle of 30o

(b) The speed of light in water 6 Figure shows a glass block with the length
of 18cm and refractive index of 1.5.
There is a bubble in the glass block.
When the bubble is seen from one side,
it appears at a distance of 8cm from the side.
When the bubble is seen in the opposite side,
it appears at a distance d2, from the side.
Calculate the value of d2.

10 Given the critical angle of prism is 42o,

Complete the ray diagram below

2 When light travel from air to a medium

its speed is decreased by 20%. What
is the refraction index of the medium? 30o

3 The depth of a pond is 5m. What is the

apparent depth if the refractive index
of water is 4/3
42o

7 Complete the ray diagram

4
A ray of light
passing from a 45o
material to air
as shown.
Calculate the
refractive index
of the material

60o
 PHENOMENON OF TOTAL INTERNAL REFLECTION
MIRAGE Formation of RAINBOW
Hot Day

Illustration

Ray

diagram

T ρ n

of ray

Dispersion of Light
Refer to the frequency dependence of refraction
1 Air consist of layers of air with different optical __________
Higher the frequency _________ the dispersion
Identify Air in contact with ground Air further aways from ground
frequencies increases
2 is ______ & become less dense is _______ & become denser
orange green violet
than the upper layer than the lower layer

Dispersion increases
Hence, the density of air decreases from
3 Main idea
__________ air layers to ___________ air layers
Caused by __________ & _____________ of
Medium
The refractive indices decreases gradually from the sunlight passing through water droplets
4
_________ to the _________ air layer
When a horizontal Dispersion of white light into its

The light from an object passing through layers of air 1

light ray enter a ____________ colours occurs
Refraction 5 will be refracted ________________ normal
water droplet at A
due to the gradual decrease of refractive indices
At point The coloured rays undergo
2
6 Incidence angle ___________ from one layer to another layer B _______________________ & they emerge at a point C
away from

At point
When i>c, _____________________________ 3 Further _____________ occurs
C
7
normal & the rays are reflected __________________
Most refracted ray Least refracted ray
4
Refraction
The reflected rays will be refracted _________ normal
8
toward
as it moves toward the denser air layers
normal
5 Coloured rays emerge at ______________ angles to the horizontal
If the observer eye in correct position,
Formation 9
refracted ray _____________ the observer 's eye. A rainbow which consists of arched bands of colours

6 with ________ on its outer edge & ________ on its inner edge
of images
10 The observer will see an inverted image on the ________
is seen in the sky
 APPLICATION of Total internal Reflection OPTICAL FIBRE
Generally
Glass PRISM C = 42 o A prism is a better reflector
made of ____ strands
compared to a mirror
1
of glass of diameter
1 Do not produce ________ images
about 0.19mm.
Efficient in reflecting all light Each bundle consist of
2
produce a _______ brighter image tens ____________ of
2
The silvering on the mirror fine strands which is
3
is easily ______________ ______ & ________

Concept

When i > c

Comparison Copper cables Vs Optical Fibre _________________

1
MIRROR periscope GLASS PRISM periscope is occurred
Cost
Two glass prisms is a prism periscope
After ______ repeated
that arranged in a way similar to the Weight
total internal reflection,
mirrors used in a simple periscope Capacity
to transmit 2 the rays emerge
Light rays from the object signal/time from the other end with
Disruption of
incident normally on one side _________ loss
signal by
Electric & of intensity
of the first prism pass __________ on
magnetic field
Application
until they strike its hypotenus face
Signal loss
at an angle of 45o 1
Distance between
Amplication
i c 2
station

The rays are totally internally ________

before entering the next prism Red Plastic Reflector on rear Lamp CAT EYE
Advantages
Prism The rays are totally __________ reflected
Can re-invert the image fromed by
______ when strike on the hypotenus face
Binoculars 1
the objective lens into an upright image of the next prism before reaching
the eye of the observer
They are effectively "fold" the length
of the binoculars (make it shorter)
2 Image formed ______ object
as compared to telescope which
has the same magnifying power
is _________ can be seen
(about 3 x)
 11 15 20
PUSAT TUISYEN ALPHA DINAMIK [ 010 218 8307]

Form 4 Chap 6 Light - Refraction Prepared by Alfred Lim

Figure above shows a ray of A light ray incident on a

1 A spoon appears to be bent when 4 Half the length of a rod is 7 light passing through a certain rectangular block X at angle of
immersed in water. Why does inserted into water. The portion A ray of light shines through from type of liquid and air. incidence α is shown above.
this occur? that has been immersed air into a block of glass as shown Calculate the refractive index Which of the angles A, B , C
A The density of light from water appears bent. This is due to the above. What is the refractive of the liquid and D is the critical angle?
to air decreases A larger density of water index of the glass block A 1.15 C 0.50
B The spoon is bent by water which causes the bending . A 0.32 C 1.61 B 0.87 D 2.00 21
C Light rays from water to air B Light waves are diffracted B 0.53 D 1.51
experience refraction when they come through the Figure above shows an incident 16
D The density of water is lesser water-air boundary ray AB passing through a 12 Total internal reflection happens
than air C Light is refracted towards the paraffin oil and diamond. Which only if A ray of light strikes a surface
normal when light emerges one of the following ray emerges A Light is incident from a less of a glass prism at an angle of
2 from the water-boundary after point B dense to a denser medium incidence, θ. The path of the
D Light is refracted further away [ndiamond = 2.4 & nparafin oil = 1.4] B The angle of incidence is light ray through the prism is as
from the normal when it A 1 C 3 larger than the critical angle Figure above shows a light rays shown above. The critical angle is
passes through the water-air B 2 D 4 C The angle of incidence is from water heading towards A p C r
boundary not equal to the angle of the water-air surface. Determine B q D s
The figure show a light ray reflection the critical angle between the
is passing through from medium 5 8 air water surface. 22 A light ray travels from a perspex
A to medium B. Which of the 13 Which of the conditions listed A 32o C 42o plate into air. Which of the
following is the possible material in the following table is a B 34o D 48o following pairs is the possible
for medium A and B? requirement for total internal values of the angle of incidence
Medium A Medium B reflection to occur? 17 (i) & the angle of refraction (r)?
A Glass Alcohol Figure above shows a path of [nperspex = 1.47]
Symbol Condition
B Glass Diamond light which shines through from i r
C Water Perspex air into water. What is the value The ray of light travels A 80.0o 53.3o
Figure above show the path of a of R if the angle of incidence from a medium to an B 20.0o 50.0o
J
3 ray of light through a glass block. is 55o? [nwater = 1.33] optically less dense Figure above shows light ray XO C 36.0o 60.0o
o o
The refractive index of the glass A 28 C 38 medium incident on the glass-air
block is represented by B 35o D 62o The ray of light travels boundary. Given that the critical 23 Which one of the following
sin x sin y from a medium to an angle of glass is 42o. Which diagram show the path of a ray
A C K
sin y sin z 9 When light passes from air into optically denser is the following represents the when it passes through a prism?
sin w sin x transparent material at an angle medium light ray after it passes through (cprism = 42º)
B D
Figure above shows a ray light sin x sin z of incidence of 60o, the angle The angle of incidence point O?
travelling from medium 1 to 2. of refraction is 45o. What is the L is greater than the A OP C OR A
Which of the following statement 6 angle of incidence when the critical angle B OQ D OS
in the following is true? angle of refraction is 30o? A J C K&L
I The optical density of medium A 24.1o C 37.8o B L D J&L 18 If the critical angle of a material
B
1 is greater than the optical B 25.0o D 40.0o is 30o, find the refractive index.
density of medium 2 14 Since the critical angle of water A 0.3 C 1.2
II The speed of light in medium Figure above shows a ray of 10 A light ray travels through a is 48.8o , a fish beneath the water B 0.5 D 2
1 is greater than the speed light travelling from glass to air glass block to air. The angle of sees a normally 180o horizon to
C
of light in medium 2 at an angle of incidence of 40o. incidence is 20.0o while the horizon view above the water 19 Find the critical angle of a
o
III The angle of incidence is Determine the value of p. angle of refraction is 34.1 . Find which will subtend within an diamond. Given the refractive
greater the than critical angle [Refractive index of glass = 1.5] the refractive index of the glass angle of index of diamond = 2.42
A I C I & II A 79.4o C 60o A 0.58 C 1.64 A 48.8o C 180o A 0.43o C 23.4o D
B II D I & III B 74.6o D 15.4o B 0.61 D 1.70 B 97.6o D 360o B 22.68o D 24.4o
24 27 1 A light ray is incident (i) Calculate the angles b) Why the fish can see a jellyfish behind a barrier?
on a triangular block of the refracted ray (i) Explain briefly with a diagram
from air as shown. when it passes to
The refractive index and out to the block.
of the block is 1.6.
Figure above shows an ice prism.
A ray of light strikes a surface of
prism as shown. If the critical Figure above shows light ray X (ii) Critical of angle of the water. (nwater = 1.33)
angle of ice is 50o, which of from air heading to a semi-circular
the following diagram shows glass block. Which one of the
the correct path of the ray of following light ray happens to be
light? (nprism = 1.45) the light ray after the light ray X (ii) Draw the appropriate rays
travels through the point O? in the diagram.
(Given critical angle = 42º) 4 Figure below shows the formation of mirage in the desert which is
A P C R due to total internal reflection.
B Q D S

28 2

Images of camels

a) State the conditions for total internal reflection

Mary put a straw in a glass of water. She looks at the straw
Figure above shows a ray of light appears to be larger and also broken at the water interface as
OA with an angle of incidence shown above.
of 42o and passes through the a) Explain why the straw appears to be larger and also broken.
glass-air surface. If the critical
Light at the air-water interfaces is _____________,
angle is 42o. Determine which
rays of light will emerge
thus the straw appeared _______. Also the _________
25 A ray of light A OB & OD C OD & OF
strikes a surface B OC & OB D OE & OD
glass causes the light rays to _______ and it act as__________
of a transparent b) Draw a diagram to show
prism normally. how an optical fibre makes
glass that make the straw appear _________.
The onward path use of total internal reflection.
of the ray of
light is as shown above. What b) State what she observes from above the glass with a ray diagram.
is the refractive index of the c) Practically, the light degrade when they travelling along the optical
She observed that the straw appeared to be bend upwards
transparent material? fibre. Why?
A 1.15 C 1.56
B 1.13 D 1.63 3
Answer
26 1 C D D
2 A B C
3 A D D d) Some optical instruments, such as periscopes use two prisms
4 D B D for the transmission of light. Light typically enters perpendicular
5 C D C to the face of the prism, undergoes total internal reflection and
Which of the light ray labelled 6 D C B then exits out of another prism
A, B , C and D is the refracted 7 C D A In Figure above, a boy stands on a beach and sees a fish in the sea (i) Draw a simple diagram
ray after light ray X passes 8 C D B and the position of the image of the fish. to show the structure
point O? 9 C D a) Draw a ray in figure above to show how he can see the fish of a periscope.
[critical angle of glass is 42o] 10 C C in the sea and the position of the image of the fish
 (ii) Explain briefly why manufacturers prefer to use prisms c) Total internal reflections (e) Figure shows a ray of light PO
instead of mirrors inside periscope. in a diamond which gives which produces a refraction angle
the diamond its sparkle. of 90o. If ΔPOQ's angle= 66.5o
Prism will allow light to undergo _________________
(i) If glass was cut into the (i) the value of critical angle for
shape of the diamond, why the block. [2 marks]
__________ while mirror allow light to undergo both
does it not sparkle like a diamond?
[critical angle for diamond & glass = 24.4o & 42o respectively]
________ and _________. Therefore, a prism reflects
o
The critical angle of diamond is 24.4 is much ______ than
(ii) The semicircular block's
_______ the incoming light but a mirror only reflects
o. refractive index [2marks]
the critical angle of glass about 42
______ of the light. It is therefore ____________
Therefore, the chances of total internal reflections to occur
enough to use a mirror in a periscope
6 A student stand in front of a plane mirror. She wears a T-shirt,
on the glass would be significantly ________ than the diamond.
which has the words "SPORTS PLAYER"
5 (a) State the conditions for total internal reflection to occur (i) State four characteristics of the image formed the words
Hence, it does _____sparkle like a diamond.

(ii) why does a diamond normally have a shape like figure above?

This shape allows most of the light entering the diamond from

(ii) Use a ray diagram to show

_____facets to be total internally reflected at the _____
how the alphabet "P" placed

P
(b) Figure below shows that the critical angle is equal to 42o when in front of plane mirror
and_____facets in such a way that they will only exit the
light ray passes from glass to air. is formed.

diamond through the _____ facets.

(iii) Give one daily example, which makes use of the image formed
This allows the diamond to give its brilliant sparkles when
by a plane mirror.

viewed on the_____.

(d) Figure below shows a transmission of light in an optical fibre.

Based on the figure above, compare and discuss whether

total internal reflection of light ray occurs in each case. [3 marks] b) A beam of parallel light is incident on a plane mirror at an angle
Figure (a) of 60° with the normal of the mirror.
(i) What is the angle of reflection?
____ total internal reflection of light ray because angle of incidence
The optical fibre is widely used in telecommunication cables (ii) Draw the ray diagram.
to transmit signals through laser.
is______ than critical angle, (i )
(i) State the physics principle behind the optical fibre.
Figure (b)

Total internal reflection of light ray is___________ to occur at

(ii) State the advantages of using optical fibre to replace the
copper wires in telecommunication (iii) State the laws of reflection
the critical angle, (i )

Figure (c)

Total internal reflection occurs for angle of incidence ______

than the critical angle, (i )

 A motion where object in
Oscillation a moves ________ and ______ along Vibrating act as source to transfer of ________ by vibration from one point to another

(Vibration motion) a _______ path about a _______ central point System without the _________ transfer of the medium between the two points

Example Type of Graph Important Definition

Simple Pendulum Displacement vs Time Profile of one particle Period (T) Time taken to _____________ ONE oscillation

number of _________ oscillations made

T = Frequency (f)
by a vibrating system in ______ second

Natural Frequency of a system which oscillates ______

f =
Frequency without the action of __________ force
Path for
→ → → → __________ displacement
a complete Amplitude (A)
→ → → → from its ______________ position
oscillation

Point that vibrate in ________ direction with

Point in phase
Weighted Spring ___________ displacement at any given time
Displacement vs Distance Profile of wave at instant time
Distance between successive _________
T =
of the ________ phase in wave

Distance between two successive

f = Wavelength (λ)
________ in a wave
Path for
→ → → → Distance between two successive
a complete
→ → → → _________ in a wave
oscillation
Important Formula

waves of water 1 Distance λ

crest Energy vs Displacement f =
T
v =
Time
=
T
= fλ

2
Energy α Amplitude

Amplitude Energy

Amplitude Energy
Trough
 TYPE of Oscillations

FREE Oscillations DAMPED Oscillations FORCED Oscillations

The amplitude of oscillates system The amplitude of oscillates system An oscillatory system that forced to oscillate
Definition
is _________ & will ___________ decrease with time & finally ___________ with a frequency other than its ______ frequency
by external force
Displacement

Illustration

Time (s)

Amplitude Constant Decreased

A A Energy lost to work done
_____ energy
λ λ
Oscillation will not stop constant will stop against the ________ force
f f
lost
Energy in E E
Constant Decreased which _______ the motion
System

When
Two causes of damping RESONANCE
Frequency by Natural frequency
Phenomena when
=
external force of the system Maximum amplitude in
Internal Damping External damping the system produced when

Due to __________ resistance Due to _________ frictional force ___________ amplitude

=
from the particles which undergo will be produced
(e.g : air resistance/ frictional force) frequency frequency
compression & rarefaction

Part of the energy in the oscillating system is used to

___________ against these _________ force

Oscillation finally ____________

 10 Five identical springs, P, Q, R, S 14 The figure shows the motion 20 Figure below shows the
PUSAT TUISYEN ALPHA DINAMIK [ 010 218 8307] and T are arranged in spring of a transverse wave along propagation of a water wave
systems as shown in figure a slinky spring. on the surface of water of
below. Each spring system B uniform depth.
Form 5 Chap 1 Water waves (Part 1) Prepared by Alfred Lim
supports a mass m and the
spring systems oscillate at D
C
1 Which of the following displace- 5 The displacement-time graph of 8 A hacksaw blade is oscillating frequencies of f1, f2 and f3 as A
ment-time graphs represents a a wave is as shown in the horizontally as shown in the shown in the figure.
wave with period of 0.05 s? figure. figure. Which distance represents the Find the wavelength of the
A amplitude? wave.
A 5 cm C 18 cm
15 A dipper produces plane waves B 10 cm D 36 cm
at the rate of x waves per
second in a ripple tank. The 21 Water waves were produced
Which of the following shows wavelength of the plane wave in a ripple tank using a vibrating
B the relationship between the is λ cm. What is the wavelength beam with frequency of 8 Hz.
From the graph, the amplitude The displacement-time graph of frequencies f1, f2, and f3? of the plane wave if the dipper What is the speed of the waves
and frequency of the wave are the hacksaw blade is A f1 = f 2 = f 3 C f 2 > f3 > f 1 produces 2x waves per second? if the wavelength of the waves
A 0.2 cm, 50 Hz A B f1 > f 2 > f 3 D f 3 > f1 > f 2 A 2λ C 1/2λ is 2 cm?
B 0.3 cm, 33 Hz B λ D 1/4λ A 0.5 cms-1 C 4.0 cms -1
-1
C 0.4 cm, 50 Hz 11 Figure below shows the B 1.0 cms D 16.0 cms-1
C D 0.4 cm, 67 Hz displacement-time graph for the 16 When the amplitude of a wave
oscillation of a weight on spring. increases its 22 The period of a simple pendulum
6 The displacement-distance B A frequency will decrease is T. If the length of the pendulum
graphs show the cross sections B period will decrease is increased four fold, its new
of water waves. Which wave C energy will increase period will be
has the largest amount of D wavelength will increase A 0.5 T C T
2 A student counts his heartbeats energy? B 1.4 T D 2T
and finds that it makes 80 beats A C Which of the following is true 17 A student set up an oscillating
in 1 minute. What is the period for the system? loaded spring. The student 23 The period of an oscillating
of his heartbeat? Amplitude Frequency observed that the loaded spring spring is not affected by
A 0.0125 s C 0.75 s (cm) (Hz) stopped oscillating after a while. A the elastic constant of the
B 0.025 s D 1.50 s A 4 4 This observation is due to spring
D B 4 2 A interference C damping B the mass of the load on the
3 The figure shows the displace- B C 8 4 B diffraction spring
ment-distance graph of an D 8 2 C the acceleration of gravity
oscillating system with a speed 18 The natural frequency of a D air resistance
of 36 cms-1. 12 A student set up an oscillating loaded spring will vary by taking
loaded spring. The student the following steps except 24 If a soprano sings with a high
9 The figure shows the displace- observed that the spring A Increasing the mass of the note, a thin piece of glass may
C ment-time graph of a wave. stopped oscillating after awhile load break. This phenomenon is
This observation is due to B Using a shorter spring called
A Interference C Damping C Using a different material A diffraction C resonance
What is the frequency of the B Diffraction for the spring B interference
system? D Pulling the spring harder
A 2 Hz C 6 Hz 13 What will happen to the total 25 What will happen to the total
B 4 Hz D 10 Hz energy of an oscillating system 19 It is observed that a washing energy of an oscillating system
7 The frequency of a simple which is oscillating at its natural machine vibrates quite violently which is oscillating at its natural
4 For the propagation of a wave, pendulum depends on From the graph, the frequency frequency without damping? at a particular speed. This is frequency without damping?
its wavelength is not based on A the mass of the bob of the wave is approximately A It increases due to A It increases
A frequency C velocity B the length of the pendulum A 1.7 Hz C 2.5 Hz B It decreases A inertia C resonance B It decreases
B medium D amplitude C the shape of the bob B 2.0 Hz D 3.3 Hz C It remain constant B momentum D rotation C It remains constant
1. A student carried out an experiment to investigate the relationship 2. An experiment is carried out to determine the gravitational 3 Figure below shows a Barton's pendulum which consists of five simple
between the frequency of vibration, ƒ and the length of stretched acceleration at a certain place. pendulums hanging on a horizontal string. When Q is pulled and
wire, ℓ at a constant tension. The student used different length of A simple pendulum is set up as shown in figure below. A stopwatch released, it will cause the other four pendulums to oscillate.
stretched wire and recorded the corresponding frequency of is used to time 20 complete oscillations for different values of ℓ.
vibration with the help of an electronic stroboscope. The results of
the experiment are shown in a graph ƒ against 1/ ℓ shown in figure
below.
(a) Why do the other pendulums start to oscillate when Q is
pulled and released?

Table below shows the readings obtained in the experiment.

Length of Time of 20 Period of
pendulum, oscillations, oscillation, T 2 (s 2 )
ℓ (cm) t (s) T (s) (b) What is the name given to the oscillation
40 25.4 of pendulum W, X, Y and Z?
50 28.6
60 31.4 c) Which pendulum will oscillate with the maximum amplitude?
(a) State the relationship between ƒ and ℓ. 70 33.5 Give a reason for your answer?
80 36.1

(a) Based on the information obtained in this experiment, state

(i) the manipulated variable,

(d) Which is the name given to the

(ii) the responding variable,
phenomenon that occurred in part (c)?
(b) Calculate the frequency of (c) Calculate the gradient of the
(iii) a fixed (controlled) variable.
vibration of the stretched wire graph of ƒ against 1/ ℓ. 4 Figure (a) below shows an oscillating system consisting of a loaded
if its length is 50.0 cm. spring. Figure (b) below shows the displacement-time graph of the
(b) Complete table above with values of period, T and T2 oscillating system.
(c) Based on table above, draw the graph of T2 and ℓ. (a) (b)

From the graph of ƒ against 1/ℓ,

(d) From your graph,
(i) state the relationship between T2 and ℓ,

(d) Using the value of the gradient

k√ T (ii) calculate the gradient of the graph. (a) (i) From the graph in figure (b), describe the oscillations of the
in (c) and the formula ƒ =
ℓ loaded spring.
where k2 = 2209 m kg-1,
calculate the magnitude of
tension T in the wire.
(e) Calculate the gravitational (ii) Explain your answer in (a)(i).
acceleration, g from the formula Answer
g = 4π2 / 100m, where m is 1 B A A C D
the gradient of the graph. 2 C B C C D
3 C C C D C
(d) State one precaution that should be taken during this experiment. 4 D A D C C
5 B D C C C

(b) Name the concept observed

in this oscillating system. [1 mark]
 WAVE
Produced by vibrating system GROUP of wave Type of wave
Phenomenon where ________ is PROGRESSIVE wave STATIONARY wave
transferred through ____________ Mechanical Electromagnetic
from one point to another wave wave
Wave that Wave that
________ physical transferring
___________ medium _______ required medium Produced when two identical progressive wave
of matters

to propagate to propagate moving in opposite directions superimposed

Wave Front with one another.
Line/plane that join all the crests E.g
The wave profile _____________ Wave The wave profile ________ propagates
musical
which are in phase
in the direction of propagation Profile in the direction of propagation instrument
& same distance ________ ________
E.g ________ wave
Energy is __________ along _____ energy is transferred 1 Guitar
from the source of the wave wave wave
Energy
the direction of propagation along the direction of propagation 2 ukulele
Circular wave front PHENOMENA of Wave Every point has the The amplitude varies from a
3 flute
Amplitude
Reflection Diffraction __________ amplitude ________ to ____
4 drum,
All particles vibrate at the All particles vibrate at the
Frequency
_________ frequency same frequency

Transverse wave Longitudinal wave

Plane wave front

Refraction Interference

Wave in which the direction of vibration Wave in which the direction of vibration

of particles in the medium is at of particles in the medium is at

Plan

to the direction of propagation of the wave to the direction of propagation of the wave
Point Points that vibrate in same direction with
view
in phase same displacement at any given time ______ wave & ________ wave E.g _________ wave
 Phenomenon of Wave (I) PATTERN OF REFLECTION
REFLECTION of waves Difference type of wavefront onto the difference type of reflector
Type of
Incident wave, reflected wave & normal
reflector Plane Convex Concave
Type of
lie in the ________ plane which
wavefront reflector reflector reflector
1
is perpendicular to the reflecting surface

at the point of incidence

Angle of incident Angle of reflection

Plane
2

Frequency f

3 Speed v

Wavelength λ
wavefront

Circular

wavefront

λ incident λ reflected
 Phenomenon of Wave (I)

REFRACTION of waves
Changes in the ________

of waves propagation due to the

change in the ______ of wave

when the wave propagate from

one medium to other medium

Sea
At middle of the sea Approaching the beach
(different ________)
Wavefront are almost _______ depth of water λ
Water depth Deep water Shallow water
because of _______ depth ________ v
Frequency f
The energy of water at bay is spread to a _______ area
Speed v
as compared to the region near the cape
______ seem stationary
Wavelength λ Amplitudebay Amplitudecape
compared to ______

Function Main idea Equation

Stroboscope To study the frequency & motion of To _________ and capture =

an object for a certain time interval the movement of moving object.

1 Water ripples in two areas of water (b) λdeep & λshallow 2 A plane wave has a wavelength of 2 cm & speed of 10ms-1 as it moves
with different depths. over the surface of shallow water. When the plane wave moves into
= =
The frequency of the stroboscope an area of greater depth, it speed become 16ms-1. Calculate fdeep & λdeep.
is 5 rotations per second and has 4 silts.
= =
6cm
= =
(a) Frequency of dipper (c) v deep & vshallow

= = = = =

= = = = =

= = = =
10cm
 12 When water waves pass from 16 The figure shows a vibrating 18 The figure shows a tilted water
PUSAT TUISYEN ALPHA DINAMIK [ 010 218 8307] deep water into shallow water, beam creating plane waves tank.
how do the wavelength and moving towards the shallow
speed change? end of a water tank.
Form 4 Chap 5 Water waves (Part 2) Prepared by Alfred Lim
Wavelength Speed
A Decreases Decreases
1 Water waves were produced 5 What will happen to the total 9 The diagram shows plane water B Increases Decreases
in a ripple tank using a vibrating energy of an oscillating system waves travelling towards a C Increases Increases When the spherical dipper
beam with frequency of 4 Hz. which is oscillating at its natural straight reflector. D Decreases Increases vibrates, the waves pattern
What is the speed of the waves frequency without damping? It is given that ƒ is the frequency formed is
if the wavelength of the waves A It increases 13 When a water wave travels of the wave at a distance, d A
is 2 cm? B It decreases from a region of shallow water from the vibrating beam. Which
A 0.5 cms-1 C 4.0 cms-1 C It remains constant to a region of deep water, of the following ƒ-d graphs is
B 1.0 cms-1 D 8.0 cms-1 what is the changes in its speed, true for this experiment? B
6 If the distance travelled by a frequency and wavelength? A C
2 A transverse wave of wave- wave from a trough to its Speed Fre- Wave-
length 20 cm travels in air at a adjacent crest is 6mm, what is The angle between the incident quency length C
frequency of 4 x 103 Hz. wavelength of the wave? waves and the reflected waves is A constant constant constant
Calculate the time taken by the A 3mm C 10mm A 20° C 50° B increase increase increase
wave to travel 2 km. B 6mm D 12mm B 40° D 100° C increase constant decrease B D D
A 0.5 s C 2.3 s D increase constant increase
B 1.0 s D 2.5 s 7 In the reflection of waves, the 10 Which figure shows how water
physical quantity which will waves would be reflected by a 14 A vibrating spherical bob is
3 The diagram shows wavefronts change is straight reflector? placed in the ripple tank to 19 Figure below shows straight
of plane water waves. The A speed of the waves A produce circular waves. What wavefronts passing from deep
water waves appear stationary B frequency of the waves is the effect on the circular 17 A wooden bar is vibrating in a water to shallow water.
when the frequency of the C wavelength of the waves waves if the depth of the water specially-built ripple tank as
stroboscope is 10 Hz. D direction of the waves in the ripple tank is increased? shown in the figure.
25 cm B A Wavelength of the circular
8 Figure below shows the waves increases.
wavefronts of an incident plane B Frequency of the circular
wave on a concave reflector. waves decreases
Calculate the velocity of the C Speed of the circular waves If the frequency of the water
water waves. C decreases waves in the deep water is
A 10 cms-1 C 50 cms-1 D Amplitude of the circular The wavefronts pattern formed 5 Hz, what is the wavelength of
B 30 cms-1 D 60 cms-1 waves decreases is the water waves in the shallow
A water?
4 Figure below shows a series D 15 A spherical dipper moves up A 1.0 cm C 2.5 cm
of plane waves which appear and down to make waves in a B 1.5 cm D 3.0 cm
stationary when seen through Which statement is correct ripple tank. What will happen to
a stroboscope. about the reflected waves? the waves when the spherical B 20 Figure below shows the pattern
A The shape of the reflected dipper moves up and down at of wavefronts produced by a
waves is circular a faster rate? bar vibrating at a frequency of
B The speed of the reflected A The waves will be closer 20 Hz in a ripple tank.
waves is faster than the together C
speed of the incident waves 11 Circular wavefronts from the B The peaks of the waves
If the stroboscope has 6 slits C The frequency of the re- source at the principal focus of will be higher
and rotates at a frequency of flected waves is higher than a concave reflector will be C The waves will travel faster
3 Hz, calculate the speed of the that of the incident waves reflected as across the tank D
plane wave. D The wavelength of the re- A circular waves D The waves will travel slower What is the speed of the wave?
A 15 cms-1 C 36 cms-1 flected waves is longer than B plane waves across the tank A 17.2 cms-1 C 28.0 cms-1
B 18 cms-1 D 54 cms-1 that of the incident waves C longitudinal waves B 23.3 cms-1 D 52.0 cms-1
21 Which of the following describes 25 The figure shows the side view 1 A ripple tank is set up to investigate a water wave phenomenon. A 2 Figure shows
the effects on waves travelling of water waves propagating lamp is fixed above the ripple tank and a sheet of white paper is the scenery
from deep water to shallow from area A to area B. placed directly below the ripple tank. of a beach.
water? (a) Why must the depth of water in the ripple tank be uniform throughout?
Wave- Fre- Velo-
length quency city (a) Name the phenomenon shown in figure above.
A Decrea- No Decrea-
ses change ses [1 mark]
B Increa- Decrea- Increa- The ratio of the frequency of the
ses ses ses waves in area A to area B is (b) Plane waves are produced by the vibration of a straight edged (b) Explain how this phenomenon can occur. [3 marks]
C No No No A 1:1 C 3:2 wooden bar on the surface of the water.
change change change B 2:1 D 3:4

22 Figure below shows the pattern 26 Figure below shows a refraction

of water waves moving of a water wave.
towards the beach. The shape
of the wavefronts takes on the
contours of the beach as the
waves get closer to it. (ii) If the vibrating wooden bar produces 12 waves per second and
the distance between P and Q is 5 cm, what is the velocity of
the water wave?
If the speed of the water wave 3
is 5 cms-1 in the region of deep (a) (i) What does the term 'wave' mean? [3 marks]
water, calculate the speed of
the water wave in the region
This phenomenon is due to of shallow water.
A diffraction C reflection A 1.5 cms-1 C 5.0 cms-1 (iii) Calculate the wavelength of the water wave if the frequency
-1
B refraction D interference B 2.5 cms D 5.2 cms-1 of vibration of the wooden bar is doubled.

23 A wave source with frequency 27 Which of the following is the

of 1200 Hz emits waves with application of the reflection of
wavelength of 0.2 m. How long waves?
do the waves take to travel A Spectacles C Magnifying (ii) Explain the difference between transverse and longitudinal
6000 m? B Plane mirror glass waves [6 marks]
A 5s C 24 s (iv) What is the name of the instrument which is used to make the
B 6s D 25 s 28 There are two types of waves: moving waves appear stationary?
longitudinal waves and
24 Figure below shows a piece of transverse waves. The main
Perspex immersed in a ripple difference between these two (c) A plane reflector is placed at
tank form a shallow region. A types of waves is the an inclined angle at the centre
series of waves originating from A period of the wave of the tank. Draw the pattern .
the side AB travel towards the B velocity of the wave of the reflected wave
side CD. C number of waves per in figure shown
second
D direction of vibration of the
wave

29 Which of the following waves D D B C A B

Which of the following properties is a longitudinal wave? A D D A C B B
of a wave will change? A Microwaves N C A D C D D
A Direction C Frequency B Sound waves S D D A B D B
B Period D Wavelength C Water waves C C A C A
 Phenomenon of wave (III)
Size of
Diffraction passes through Application of Diffraction
opening/
DIFFRACTION of waves Effect obstacle
Aperture (Silt) Obstacle Protection of Port
Waves ___________ as the waves Changes in _________ of propagation
1
& pattern of the waves
pass ________ an aperture
Waves ________ energy
2
or _________ a small obstacle
to adjacent region
a <λ
Frequency f Amplitude Amplitude

Speed v
>
Wavelength λ Diffraction Diffraction

ILLUSTRATION

When sea wave hit the wall barrier,

Part of the waves Part of the waves

a=λ will propagate ______ will be _______

the gap in between the wall

The wave Sea water at port

been _________ remained relatively

_______
The amplitude of
& operation of port
waves ________
have _________

Energy perunit length

a>λ disturbance from
of the waves ______
movement of wave

Do you know? OBVIOUSLY

Your EFFORT will lead to result…
Your days
1 Diffraction effect > obvious Size of aperture Do you think your current result
are numbered
Conclusion 2 Diffraction effect > obvious Size of obstacle will help you to get scholarship?
about 45 days Reduce the burden of your family!
λbefore λafter AB4 Aaf 3 Diffraction effect > obvious λ (a ≤ λ)
to go….. What should you do….?
 Phenomenon of Wave (IV)

Interference
Produced when 2 source of waves

______ & ________ & _____________

between each other

Effect of Change in ________

interference Change in ________

Principle of SUPERPOSITION
The __________ of displacement at the point

where the waves overlap is equal to

the ________ sum of displacement produced

by the ___________ waves at the point

Superposition between Type of interference

Two

crests

ΣA = __________
Two

Antinode Antinodal line

Trough Points where Line joining

all the points where
Interference ___________
____________
Two P amplitude
r interference
o
in phase is produced
d take place
u
wave c
e
one trough d

&
ΣA =zero Node Nodal Line

One Crest Points where Line joining

all the points where
________
Two
______________
Interference amplitude
antiphase
is produced interference
wave

Interference
To SUCCESS Stay FOCUS on your goal… INTERFERENCE will derail Lead you to
Uncontrollable usage TV, internet,
in life… but away from all the INTERFERENCE you from your goal… your downfall…
phones, computer games & etc…
 Experiment for interference of water waves Important Finding
x
Condition =

Coherent Sources
Sources that have the
λ λ = wavelength
1 Same frequency
x
Distance from the sources to
Constant phase D =
2 the point of measurement of x
different
distance between
D
a =
3 Same Amplitude two coherent sources
x
Distance between two
x =
consecutive node lines
a
(or antinode lines)

Different Result of INTERFERENCE PATTERN

λ1 λ2

a1 a2

D1 D2
 13 Which of the following obser- 16 19 Figure below shows the
PUSAT TUISYEN ALPHA DINAMIK [ 010 218 8307] vations can be obtained in an superposition of two coherent
experiment with a ripple tank? waves.
A
Form 4 Chap 5 Water waves (part 3 & 4) Prepared by Alfred Lim

Figure above show two waves

1 Which of the following will 6 Select one from figure below 9 Select one form figure below moving in opposite directions
change when water waves which shows the correct which shows the correct pattern along a strected rope.
pass through a narrow gap? wave pattern. B Which of the following diagrams This process produces
A Frequency C Speed shows the correct wave patterns A constructive interference
B Amplitude D Wavelength when the two waves meet a at B destructive interference
point Z and after they passed C a strong diffraction
2 Figure below shows plane point X? D a weak diffraction
water waves approaching a slit C
between two obstacles. Answer question 20 & 21
based on the figure below

14 Which of the following shows

the pattern formed by the
The effect of the diffraction of wavefronts of water waves
the water wave increases passing by an obstacle? Fi
when λ A
A is constant C increases
B decreases 20 Figure above shows a pattern
of wave interfernece, select
3 The instrument which can be B points where destructive
used to observe the 10 For the effect of diffraction to interference occurs.
interference pattern of water 7 Figure below shows the pattern be significant, the wavelength A points X & Z C points Y & Z
waves in a ripple tank is of the wavefronts of a circular comparison to the size of the 17 Figure below shows two impulse B ponts Y & Z D points W & Z
A torch light wave observed in a ripple tank. obstacle has to be C waves travelling towards each
B stroboscope A Large C Large other along the length of a rope. 21 Select the points where the
C magnifying glass B Small Both waves meet at the point O. amplitude is the highest
D colour filter A points X & Y
11 Interference pattern of two D B points Y & Z
4 When a water passes through coherent water waves. C ponts Z & W
a narrow gap in a ripple tank of
uniform depth, what will happen Which of the following What is the resultant displace- 22 The figure shows an interfe-
to its frequency (f) , wavelength(λ) phenomenon is shown by the ment of the two waves at the rence pattern of two coherent
and speed(v)after diffraction? observation? 15 Which of the following diagrams point O? water waves sources P and Q.
f λ v A Reflection of waves shows the refraction of a water A -2a C a
A decreased increased Unchanged B Refraction of waves wave? B 0 D 2a
B UnchangedUnchangedUnchanged C interference of waves Which of the positions does A C
C increased Unchanged increased D Diffraction of waves constructive interference occur? 18 Which of the following
D Unchangeddecreased increased A P and Q C Q and R statements is true about
8 Diffraction of waves is caused by B P and R D Q and S coherent waves?
5 If a wave motion has a frequency A a change in the direction of A Coherent waves have the
of 2.5Hz and a velocity of propagation of the waves 12 Interference of waves can be B D same colour
10cms-1the wavelength of the B an increase in the speed of explained by the B Coherent waves are in Constructive interferences
wave motion is the waves A principle of buoyancy phase occur at
A 0.4cm C 25cm C the spreading or bending of B principle of superposition C Coherent waves have the A I C I, II and IV
B 4 cm D 0.25cm the waves C principle of conservation same amplitude B I and III D I, II, III and IV
 Answer question 23 & 24 & 25 27 Figure below shows two 30 A student used a ripple tank to 31 In an experiment to study the 2 Figure below shows
based on the figure below transverse pulses along a rope. study the refraction phenomenon interference of water waves, a portion of an island.
of water waves. Which of the coherent waves of frequency During the monsoon
following observations is true? 50 Hz is used. The distance season, waves are
A between the two sources of big and may erode
Which of the following obser- waves is 0.1 m and the speed the seashore.
vation is true when the two of the waves is 2 ms-1.
pulses meet at point X? Calculate the spacing between
23 Figure above shows a pattern A two consecutive lines of
of wave interference from B destructive interference at a
two coherent sources S1 & S2 distance of 0.5 m from the To attract more tourists to the island, a contractor wants to build a
which are 10cm apart. Given B source of waves. beach resort equipped with safety features for tourists to stay in
that the distance between A 0.1 m C 0.3 m the resort and swim in the sea.
consecutive nodes is 6cm and B 0.2 m D 0.4 m You are asked to give suggestions on the proposed project based
the perpendicular distance of C C on your knowledge of the phenomena of waves and the
measured nodes form S1 and S2 ANS following considerations: [10 marks]
is 20cm, the wavelength will B D A B A B B (i) the location of the resort,
work out to be D C D B B B C
A 33cm C 3cm B C A B C B
B 3.3cm D 0.3cm B A A B D D
28 A student carried out an B C C D C C
24 Which line is known as the line experiment to investigate the
of constructive interference? interference of sound waves. 1
A R C N If the manipulated variable in
B S D P this experiment is the distance
between the two speakers,
25 Refer to x and a in the same which of the following is the
figure, which reflects the responding variable?
correct relationship? A Wavelength of the sound (ii) features to reduce erosion of the shore,
waves
B Distance between two
consecutive antinodal lines
C Speed of sound waves Figure above shows the wavefronts of the sea waves entering
into a bay.
(i) State the phenomena observed in the diagram. [1 mark]

(iii) features to enable children enjoying relatively calm water.

(ii) Compare the amplitude of the waves before and after entering
the bay. Explain your answer. [3 mark]

29 Figure above shows the

interference pattern produced
by two vibrating sources S1
26 Two sources of waves are and S2 in a ripple tank.The
coherent if wavelength of water wave is
A their periods are different 3.0cm . What is the distance x
B they have the same between two nodal lines 25cm
frequency from S1 & S2?
C their wavelengths are A 10cm C 5cm
different B 20cm D 15cm
3 Figure (a) below shows the arrangement of the apparatus for an 4 Figure below shows a continuous stream of straight waves of (c) Design an experiment to investigate the hypothesis stated in (b).
experiment to study a wave phenomenon. A student observed the frequency 25 Hz produced in a ripple tank. A straight metal barrier Choose suitable apparatus such as ripple tank with its
waves pattern formed on the screen with the help of a stroboscope. with a gap in the centre is placed in the ripple tank. accessories and other apparatus.
Figure (b) below shows the wave patterns observed by the student. (a) Draw the water waves in your description, state clearly the following;
after passing through (i) aim of the experiment,
the gap in the barrier. (ii) variables in the experiment,
(a > λ) (iii) list of apparatus and materials,
(iv) arrangement of the apparatus,
(b) Name the phenomenon (v) the procedure of the experiment, which includes the
which you have drawn method of controlling the manipulated variable and
in (a). the method of measuring the responding variable,
(vi) the way you would tabulate the data,
(vii) the way you would analyse the data. [10 marks]
(i) To show the relationship between the width of the gap
(a) (b) (c) Draw the change/changes and the amount of diffraction of the waves.
(a) (i) Explain how the patterns are formed on the screen. [4 marks] which might occur when (ii) - Manipulated variable: The width of the gap
(i) the size of the gap in the - Responding variable: The amount of diffraction
metal barrier is reduced. - Fixed variable: Frequency of the waves
[2 marks] (iii) Ripple tank with its accessories, stroboscope, protractor,
white paper as screen.
(iv)
(d) The distance across 10 consecutive water waves is 20.0 cm.
Calculate the speed of the waves. [4 marks]

(ii) Observe figure (b) above. Compare the frequencies, (v) (1) The apparatus is set up as shown in the figure in (iv).
wavelengths and speeds of the waves at deep and shallow 5 A boy looked down from the (2) The legs of the ripple tank are adjusted so that the
areas of the ripple tank. Relate the speed and the direction of aeroplane he is travelling and depth of the water is uniform.
wave motion to deduce a relevant physics concept. [5 marks] observed the sea waves (3) Two barriers are adjusted to produce a small gap.
moving into two bays. Figure (4) The motor is switched on and the rheostat is
shows the waves that adjusted to produce a low frequency of the waves.
passed through the gaps (5)The pattern of the diffracted waves is observed.
between the concrete walls.
(vi) Diffraction patterns for increasing width of the gap:

Based on the boy's

observations;
(a) Make one suitable inference that can be made.

[1 mark]

(b) State one appropriate hypothesis for an investigation. (vii) From the pattern observed, the smaller the width

of the gap, the more the waves will be diffracted.

(iii) Name the wave phenomenon

The hypothesis is accepted.
shown in figure (b). [1 mark]