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lectures some of the details explained in

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understanding

3.2 Light

Robila Imran 1
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Reflection Of Light
The Laws of Reflection
•The angle of reflection is equal to the angle of incidence
Angle of incidence (i) = Angle of reflection (r)
•The incident ray, the reflected ray, and the normal to the surface of the mirror
all lie in the same plane.

Physics Test # 1
Topic 3.1: General Properties of Waves

Date:4-9-2024(Wednesday)

Robila Imran 2
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understanding
900-400=500

<r =500

900-430=470
900-430=470

<r =500

Robila Imran 3
 B C

This is a teaching resource used to give 9/6/24

lectures some of the details explained in
A D
class may not be present in these sldies plane
9
please refer to class notes for full mirror
understanding
20 An object is placed 30 cm in front of a plane mirror.
eye
Q21/W22/P22 object
Which statement describes the image of the object?

A The image is the same size and 30 cm from the object.

21 The angle between an incident ray and the surface of a plane mirror reflecting the ray is 70°.
B The image is the same size and 60 cm from the object.
What is the angle of incidence?
C The image is smaller and 30 cm from the object.
AD 20° B 40°and 60 cm from
The image is smaller C the
70°object. D 140° A
Q21/W22/P21
22
21 The diagram
A ray of lightshows the onto
is shone air molecules in part
the surface of a of a sound wave at a particular moment in time.
mirror.

X
2 3
1 4

Which two angles represent the angle of incidence and the angle of reflection? C
Which statement is not correct?
A 1 and 2 B 1 and 4 C 2 and 3 D 3 and 4
A Earlier, there was compression at X.

7 22 BTheLater,
speedthere will beinaair
of sound rarefaction
is 330 m /at
s. X.
CHow
This
do part of the wave
the speeds is travelling
of sound horizontally
in concrete across
and water the page.
compare with this speed?
D This part of the wave is travelling towards the top of the page.
speed in speed in
concrete water
23 Q23/W19/P22
An object is reflected in a plane mirror. 9
A 23 greater greater
A ray of light is incident on a plane mirror. A student measures the angle of incidence i and the
Which description
angle of reflection r. is correct?
of the image
B greater less
A diminished and real
C less greater
B enlarged and virtual incident i r reflected
D less less
C same size and real ray ray

D same size and virtual

23 What is the speed of microwaves in air?
The student varies the angle of incidence and then plots a graph of r against i.
3
A 2022
© UCLES 108 m / s 0625/22/O/N/22
What does the graph look like?
8
B 3  10 cm / s
A B C D C
C 3  108 m / s
r r r r
D 3  108 km / s

0 0 0 0
0 i 0 i 0 i 0 i

8 24 What is monochromatic light?

A light of a single amplitude

© UCLES 2022 B light of a single frequency 0625/21/O/N/22 [Turn over

Robila Imran C light of more than one colour 4
D light which travels with constant velocity

25 The diagram shows the electromagnetic spectrum.

 through the hill.

Which row is correct?

A possible way A stronger signal is

This is a teaching resource
for used
this toto give is
happen received using 9/6/24
lectures some of the details explained in
class may not beApresent
diffraction round the hill.
in these sldies longer wavelengths.
please refer to class
B notes for full
diffraction round the hill. shorter wavelengths.
understanding C refraction round the hill. longer wavelengths.
D refraction round the hill. shorter wavelengths.

Q22/W19/P21
22 The diagram shows the image of a clock in a plane mirror.

Which is the actual time? C

A 04:15 B 04:45 C 07:15 D 07:45

20 Which diagram shows the image correctly formed by reflection?

A B
Q20/W23/P22
object image object image

© UCLES 2019 0625/21/O/N/19 [Turn over

mirror mirror

C D
object image object image

D
mirror mirror

21 A student passes parallel rays of light through four different converging lenses. He measures the
distance x and the distance y for each experiment.
10

Robila Imran 5

y
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understanding

11

Image formation by a plane mirror

When a light reflects from a plane mirror , it forms an image with these characteristics
• Upright
• Same distance from the mirror as the object
• Same size
• Laterally inverted*
• Virtual *
*A virtual image is formed by the divergence of rays from the
image, and cannot be projected onto a piece of paper or screen
(because the rays don’t actually go through the image)
*Laterally inverted means image in which left and right side are reversed.

12

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understanding

13

13

9 (a) Fig. 9.1 shows two rays of light X and Y leaving an object O. The rays strike a plane mirror.
Ray X is reflected as shown.
Q9/M20/P32
plane
mirror

ray of light
X O
ray of light
Y

Fig. 9.1

(i) On Fig. 9.1, draw the normal at the point where ray X strikes the mirror. [1]

(ii) On Fig. 9.1, draw the path of ray Y after it strikes the mirror. [1]

(b) An object O is placed on the left of a thin converging lens. F is the principal focus.

This arrangement is shown in Fig. 9.2.

14
lens

Robila Imran 7

O F
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understanding 13

25 Which diagram shows how the light from a candle is reflected by a mirror, and shows the position
of the image formed?
Q25/M20/P22 A B

image of image of
candle candle
candle candle

eye

A
eye
mirror mirror

C D

candle candle

image of
candle eye

image of eye
candle
mirror mirror

15
26 A converging lens can be used as a magnifying glass.

What will be the nature of the image?

A real, inverted, diminished

9
B real, upright, enlarged

22C An
virtual, inverted, enlarged
object O is placed in front of a plane mirror as shown.
D virtual, upright, enlarged

O
Q22/S20/P22 plane mirror

© UCLES 2020
1
0625/22/F/M/20
2
[Turn over

Which row is correct?

position of nature of
the image the image

A 1 real
B 1 virtual B
C 2 real
D 2 virtual

16 23 Which statement is correct?

A The speed of light in glass is equal to the speed of light in a vacuum multiplied by the
refractive index of glass.
B The incident angle of a light ray at an air-glass surface is the angle between the ray and the
Robila Imran glass surface.
8

C The sine of the critical angle at an air-glass surface is equal to 1 .

refractive index of glass
D The angle of refraction for light passing through an air-glass surface is proportional to the
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understanding 14

10 Fig. 10.1 shows two mirrors placed at right angles to each other. A ray of light is incident on
Q10/M17/P32 mirror A, which is then reflected towards mirror B.

mirror A

20°

mirror B

Fig. 10.1

(a) Determine the angle of incidence of the ray on mirror A.

angle of incidence = ...........................................................[1]

(b) (i) The ray is also reflected from mirror B.

On Fig. 10.1, continue the path of the ray of light. Show the position of the reflected ray
and the normal to mirror B. [2]

(ii) On Fig. 10.1, use the letter r to label the angle of reflection from mirror B. [1]

(c) State the law you used to complete the ray diagram.

...............................................................................................................................................[1]

[Total: 5]

17

10

23 A student uses one eye to look at images in a plane mirror.

Q23/S22/P22 plane mirror

P Q R E S T U
X © UCLES 2017 0625/32/F/M/17 Y

Objects are placed on the line XY. B

Which objects give rise to images that can be seen by the eye at E?

A P, Q, R, S, T and U

B Q, R, S and T only
C P and U only
D R and S only

18 24 An object is placed in front of a converging lens of focal length 15 cm.

Which row describes the image of the object?

distance of object
Robila Imran from lens / cm
nature of the image 9

A 40 real, upright, diminished

B 30 virtual, inverted, enlarged
 In which diagram will the diffraction be least?

A B C D

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understanding

Q21/S19/P21

21 An object is placed 30 cm in front of a plane mirror.

Which statement describes the image of the object?

B
A The image is the same size and 30 cm from the object.
B The image is the same size and 60 cm from the object.
C The image is smaller and 30 cm from the object.
D The image is smaller and 60 cm from the object.

© UCLES 2019 0625/21/M/J/19

19

Refraction
Refraction is the change in direction of a wave passing from one medium to
another medium.
As the light enters the denser medium it slows down and bends towards the
normal(angle of refraction will be small)
When it enters the less dense medium it speeds up and bends away from the
normal (angle of refraction will be large)

20

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understanding

21

22

Robila Imran 11
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understanding

11

21 The diagram shows an object O in front of a thin converging lens of focal length f.

At which point will the lens form a sharp image of the object?

A
O

23 B

f f
C
D

Q22/W17/P22
22 The diagram shows a ray of light incident on the surface of a rectangular glass block at 90° to the
surface.

ray of light

glass block

Which quantities remain unchanged as the light enters the glass block?

A direction and frequency A

B direction and speed
C frequency and speed
D speed and wavelength

24
23 Which piece of equipment is designed to produce a type of electromagnetic wave?

A electric fire

Robila Imran B electric generator 12

C electric motor
D electromagnet
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understanding

Critical angle:
The critical angle is defined as the angle of incidence that provides an angle of
refraction of 90-degrees. The light will be refracted so that it goes along the surface
of the material

25

26

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Total Internal Reflection: (TIR)

When the angle of incidence of the light ray is greater than the critical angle then no
refraction takes place. Instead, All the light is reflected back into the denser material. This is
called Total Internal Reflection(TIR).

27

Conditions for total internal reflection to occur:

1.The incident light

2.The angle of
must be going from a
incidence must be
more dense medium
greater than
towards a less dense
the critical angle.
medium.

28

Robila Imran 14
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understanding

Refractive Index(n)
n = speed of light in vacuum or air = c
speed of light in medium v

n = Sin(i)
Sin(r )
Incase of angle of refraction in less dense medium 1/n=Sin (i)/Sin(r)

n = ____1____
Sin ( c)

29

https://learning.cambridgeinternational.org/classroom/course/
view.php?id=2989

https://learning.cambridgeinternational.org/classroom/course/
view.php?id=3725

30

Robila Imran 15
 18 The metal surface of a kettle is hot.

What happens to the cool air outside the kettle when it comes into contact with the hot kettle?
This is a teaching
A The resource used
density of to decreases
the air give and the air falls. 9/6/24
lectures some of the details explained in
B The density of the air decreases and the air rises.
class may not be present in these sldies
please referCto class notes of
The density forthe
full
air increases and the air falls.
understandingD The density of the air increases and the air rises.7
18 The diagram shows a ray of light entering a glass block.
19 Vacuum flasks usually have silvered walls that help to keep the contents of the flask hot.
Q18/S23/P21 air glass
Why are the walls silvered?

A to absorb thermal energy from the air around the flask25!

B to increase the rate of convection inside the flask
50!
C to reduce energy loss to the surroundings by conduction
D to reflect thermal radiation back into the flask
Which calculation gives the refractive index of the glass?
40 through a sin
sinpass
20 When water waves 40 sin 50 sin 50
A B gap they diffract.
C D
sin 25 sin 65 sin 25 sin 65
The diagrams show wavefronts approaching a narrow gap.
19 An object O is placed at point P near to a thin converging lens. The diagram shows three rays
In which diagram
from will theofdiffraction
the top O passing be A the lens. Each point F is one focal length from the centre of the
least?
through
lens. Each point 2F is two focal lengths from the centre of the lens.
A B C D

O
31

P 2F Q F F 2F
image

Q21 & 22/S19/P22

21 Which conditions are necessary

The object O is movedfor light Q
to point toon
bethe
totally internally reflected?
diagram.

Which type of image is produced when the object O is at point Q?

the incident light is in angle of incidence
A inverted and the same size as the object
A the less dense medium
B inverted and enlarged
less than the critical angle D
B the less dense medium greater than the critical angle
C upright and the same size as the object
C theDmore dense medium
upright and enlarged
less than the critical angle
D the more dense medium 9
greater than the critical angle

22 Light is travelling through air. The light strikes a glass block at an angle of incidence of 45°. The
glass has a refractive index of 1.4.
B
What is the angle of refraction of the light as it enters the glass?

A 29° B 30° C 32° D 82°

© UCLES 2019 0625/22/M/J/19

23 An eclipse of the Sun happens when the Moon comes between the Earth and the Sun.
32 © UCLES 2023 0625/21/M/J/23 [Turn over
Which statement is correct?

A Infra-red radiation from the Sun disappears before visible light and ultra-violet radiation.
B Ultra-violet radiation from the Sun disappears before visible light and infra-red radiation.
Robila Imran 16
C Visible light from the Sun disappears before ultra-violet radiation and infra-red radiation.
D Infra-red radiation, ultra-violet radiation and visible light from the Sun all disappear at the
same moment.
 21 Which conditions are necessary for light to be totally internally reflected?

the incident light is in angle of incidence

A the less dense medium less than the critical angle

This is a teaching resource used to give 9/6/24
B the less dense medium greater than the critical angle
lectures some of the details explained in
C the more dense medium less than the critical angle
class may not be present in these sldies
please refer to class Dnotes for
thefull
more dense medium greater than the critical angle

understanding
22 A beam of light passes through a vacuum and then enters a liquid. The diagram shows the path it
takes.

Q22/S19/P23

40°
vacuum
liquid

25°

The light travels through the vacuum at a speed of 3.0 × 108 m / s.

What is the speed of light in the liquid?

A 1.9 × 108 m / s
B
B 2.0 × 108 m / s

C 4.6 × 108 m / s

D 4.8 × 108 m / s

33 23 An eclipse of the Sun happens when the Moon comes between the Earth and the Sun.

Which statement is correct?

A Infra-red radiation from the Sun disappears before visible light and ultra-violet radiation.

Real And Apparent Depth

B Ultra-violet radiation from the Sun disappears before visible light and infra-red radiation.
C Visible light from the Sun disappears before ultra-violet radiation and infra-red radiation.
D Infra-red radiation, ultra-violet radiation and visible light from the Sun all disappear at the
same moment.

© UCLES 2019 0625/23/M/J/19 [Turn over

34

Robila Imran 17
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understanding 12

7 (a) The speed of light in air is 3.0 # 108 m / s.

The speed of light in a transparent liquid is 2.0 # 108 m / s.
Q7/S17/P42
A ray of light is incident on the surface of the liquid at an angle of incidence of 40°.

Calculate

(i) the refractive index of the liquid,

refractive index = ...........................................................[2]

(ii) the angle of refraction in the liquid.

35

13

(b) Fig. 7.1 shows a side view of an object at the bottom of a tank of liquid. Light travels slower in
this liquid than in air.

angle of refraction = ...........................................................[2]

eye

air
tank

liquid

object

Fig. 7.1

On Fig. 7.1, draw two rays from the object into the air. Use these rays to locate the image.
Label this image I. [3]

[Total: 7]

36

Robila Imran 18
© UCLES 2017 0625/42/M/J/17
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understanding 13

7 Fig. 7.1 shows light approaching a boundary between two materials at speed v. The speed of the
light after crossing the boundary is 1.3v.

Q7/S19/P43
light

50°
boundary

Fig. 7.1

(a) Determine the angle of incidence.

angle of incidence = ......................................................... [1]

(b) Calculate the angle of refraction.

angle of refraction = ......................................................... [3]

[Total: 4]
37

© UCLES 2019 0625/43/M/J/19 [Turn over

38

Robila Imran 19
 8
This is a teaching resource used to give 9/6/24
6
lectures(a)some
Fig.of6.1
theshows anexplained
details arrangement
in of glass prisms inside a box. The angles of the prisms are
45°, 45° and 90°.
class may not be present in these sldies
please refer to class notes for full box
8
understanding
6 (a) Fig. 6.1 shows an arrangement of glass prisms inside a box. The angles of the prisms are
45°, 45° and 90°.

box
Q6/S20/P42
prism 1
incident
ray of light prism 1
incident
ray of light

wall prism 2
wall prism 2

eye

eye

Fig. 6.1 (not to scale)

39
This is a device used to view objects that are behind a wall.
The incident ray of light undergoes total internal reflection in the prisms.

On Fig. 6.1, complete the path of the ray through the device and show the ray as it emerges
from the box. Fig. 6.1 (not to scale) [3]

(b) Show that the refractive index of glass with a critical angle of 45° is 1.41.
This is a device used to view objects that are behind a wall.
The incident ray of light undergoes total internal reflection in the prisms.

On Fig. 6.1, complete the path of the ray through the device and show the ray as it emerges
from the box. [3]

(b) Show that the refractive index of glass with a critical angle of 45° is 1.41.
[2]

[Total: 5]

© UCLES 2020 0625/42/M/J/20

[2]

[Total: 5]
40

Robila Imran 20
© UCLES 2020 0625/42/M/J/20
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understanding

Physics Test # 2
Topic 3.2: Light
3.2.1.(Reflection) & 3.2.2 (Refraction)

Date: 11-9-2024(wednesday)

5 (a) Fig. 5.1 shows a semicircular transparent plastic block.

41

5 (a) Fig. 5.1 shows a semicircular transparent plastic block.

semicircular
transparent
Q5/M23/P42
plastic block

Fig. 5.1

A ray of light is incident normally on the curved surface of the block. The refractive index of
the plastic is 1.5.semicircular
transparent
(i) Calculate the critical angle for the plastic.
plastic block

Fig. 5.1

A ray of light is incident normally on the curved surface of the block. The refractive index of
the plastic is 1.5.

(i) Calculate the critical angle for the plastic.

critical angle = ......................................................... [2]

(ii) On Fig. 5.1, draw the path of the ray in the block and after the ray emerges from the
block. [2]

(b) Fig. 5.2 is a full-scale diagram of a lens and an object O.

42
lens
critical angle = ......................................................... [2]

Robila Imran (ii) On Fig. 5.1, draw the path of the ray in the block and after the ray emerges from the 21
block. [2]
F O
(b) Fig. 5.2 is a full-scale diagram of a lens and an object O.

lens
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9
understanding
(b) A source emits visible light.

9
Fig. 6.2 shows a ray of red light from the source incident on the face XY of a glass prism at
point S.
Q6/M18/P42
(b) A source emits visible light. X

normal
Fig. 6.2 shows a ray of red light from the source incident on the face XY of a glass prism at
point S.
i S

ray of
X
red light
normal

Y Z

Fig. 6.2

S
The angle of incidence i of the ray is 35 °. The refractive index of the glass for red light is 1.5.
i
(i) Calculate the angle of refraction in the glass at S.

ray of
red light

angle of refraction = ......................................................... [2]

(ii) On Fig. 6.2, draw9 the refracted ray at face XY and the ray emerging from face XZ of the
43 prism. Label this ray R. [2]
(b) A source emits visible light.
(iii) YA ray of blue light follows the same path as the ray of red light incident on the
Z face XY.
Fig. 6.2 shows a ray of red light from the source incident on the face XY of a glass prism at
point S. On Fig. 6.2, draw the path of this ray in the prism and emerging from the prism.

Label this ray B. Fig. 6.2 [2]

X
[Total: 8]
The angle of incidence
normal i of the ray is 35 °. The refractive index of the glass for red light is 1.5.

(i) Calculate the angle of refraction in the glass at S.

i S

ray of
red light
© UCLES 2018 0625/42/F/M/18 [Turn over

Y angle of refraction = .........................................................

Z [2]
Fig. 6.2
(ii) On Fig. 6.2, draw the refracted ray at face XY and the ray emerging from face XZ of the
prism.
The Label this rayi ofR.the ray is 35 °. The refractive index of the glass for red light is 1.5.
angle of incidence [2]
(i) Calculate the angle of refraction in the glass at S.
(iii) A ray of blue light follows the same path as the ray of red light incident on the face XY.

On Fig. 6.2, draw the path of this ray in the prism and emerging from the prism.

Label this ray B. angle of refraction = ......................................................... [2] [2]

(ii) On Fig. 6.2, draw the refracted ray at face XY and the ray emerging from face XZ of the
prism. Label this ray R. [2] [Total: 8]
(iii) A ray of blue light follows the same path as the ray of red light incident on the face XY.
44
On Fig. 6.2, draw the path of this ray in the prism and emerging from the prism.

Label this ray B. [2]

[Total: 8]
Robila Imran 22
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understanding

Q24/S19/P11 12

24 The diagram shows light incident at a glass-air boundary. The angle of incidence i of the ray is
greater than the critical angle.

Which line shows the path of the light after it meets the boundary?

C D
air
glass i

B incident ray
B of light
A

25 The diagram shows radiation from a lamp passing through a prism.

45
screen
prism
P
Optical fibres red light

It is a device based on total internal reflection(TIR) by which light signals

may be transmitted from one place to another with negligible loss of energy.
radiation from
Uses lamp
1.Communications, such as telephone and internet transmission
2.Cable
Whichtelevision and Computer
type of radiation is foundnetworking.
at P?
Fiber optic cables transmit large amounts of data at very high speeds. Fibre optics is used for
A γ-rays and high-performance data networking.
long-distance
3.Medical imaging and surgery
B infrared
These fibres transmit light into the patient's body and enable physician to view images of
C ultraviolet
internal body structures for early detection of diseases. Endoscopes use optical fibres to
produce an image of inside the body. It is also used as lasers during surgeries
D X-rays
4.Lighting and decoration
It minimizes chances of signal leakage and electric shocks, its
lightweight, flexibility, affordable cost, long life span, etc

46

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Optical fibres in medical

Optical fibres is used as lasers during surgeries, endoscopy, microscopy and biomedical
research.
During an endoscopy doctor gently inserts a long, flexible tube, or endoscope, into patient’s
mouth, down into oesophagus/stomach. A fibre-optic endoscope has a light and tiny camera
at the end. Your doctor can use this device to view your oesophagus, stomach and the
beginning of your small intestine.

47

Optical fibres in telecommunications

Optical fibre is used by telecommunications companies to transmit telephone signals, Internet
communication and cable television.
The Optical fibre communication process transmits a signal in the form of light which is first
converted into the light from electrical signals .
The transmitter takes analogue or digital information and converts it into digital pulses that are
then transmitted through a light source. This light source is connected to the fibre optic cable
which carries the signal in the form of light pulses to the receiver. The receiver has a light
detector that reads the incoming light pulses and amplifies them so that a digital or analogue
signal can received

48

Robila Imran 24
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lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding 11

Q5/W18/P42 (b) Fig. 5.2 shows a section of an optical fibre in air. A ray of light is incident on the fibre wall at X.

X
optical fibre

ray of
Cambridge IGCSE Physics 0625light
syllabus for 2023, 2024 and 2025. Subject content

Fig. 5.2

(i) On Fig. 5.2, continue the path of the ray of light up to the end of the fibre. [1]

3.2 Light continued

(ii) The refractive index of the material of the fibre is 1.46. Calculate the critical angle of the
material of the fibre.
3.2.2 Refraction of light

Core Supplement
1 Define and use the terms normal, angle of
incidence and angle of refraction
critical angle = ...........................................................[2]
2 Describe an experiment to show refraction of 6 Define refractive index, n, as the ratio of the
light by transparent blocks
(iii) State of uses
two different shapes
of optical fibres. speeds of a wave in two different regions
3 Describe the passage of light through a 7 Recall and use the equation
1 ........................................................................................................................................
transparent material (limited to the boundaries sin i
between two media2only) n=
sin r
........................................................................................................................................
4 State the meaning of critical angle 8 Recall and use the equation [2]

1 [Total: 8]
n=
sin c
49
5 Describe internal reflection and total internal 9 Describe the use of optical fibres, particularly in
reflection using both experimental and everyday telecommunications
examples

3.2.3 Thin lenses

Core Supplement
1 Describe the action of thin converging and thin
diverging lenses on a parallel beam of light
2 Define and use the terms focal length, principal
axis and principal focus (focal point)
3 Draw and use ray diagrams for the formation of a 6 Draw and use ray diagrams for the formation of a
real image by a converging lens virtual image by a converging lens
4 Describe the characteristics of an image using the 7 Describe the use of a single lens as a magnifying
terms enlarged/same size/diminished, glass
upright/inverted and real/virtual
5 Know that a virtual image is formed when
diverging rays2018
© UCLES are extrapolated backwards and 0625/42/O/N/18 [Turn over
does not form a visible projection on a screen
8 Describe the use of converging and diverging
lenses to correct long-sightedness and short-
sightedness

3.2.4 Dispersion of light

Core Supplement
1 Describe the dispersion of light as illustrated by
the refraction of white light by a glass prism
2 Know the traditional seven colours of the visible 3 Recall that visible light of a single frequency is
50 spectrum in order of frequency and in order of described as monochromatic
wavelength

Robila Imran 25
22 www.cambridgeinternational.org/igcse Back to contents page
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding

Lenses
A lens is a transparent curved device that is used to refract light.
A lens is usually made from glass.

Converging lenses are fatter in the middle than at the edges

Diverging lenses are thinner in the middle than at the edges

51

Optical Centre(o)
Central point of the lens
Principal Axis
Straight line passing through the optical centre 900 to the lens
Principal Focus/Focal Point(F)
The point on principal axis where incident rays meet after passing through lens
Focal Length(f)
Distance between the optical center and principal focus

52

Robila Imran 26
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding
Real Image
When light rays meet or intersect and image formed is real and inverted. Real
image can be obtained on the screen.
Virtual Image
Virtual image is formed when the light rays appear to be originating from a point
but does not actually meet. It cannot be obtained on a screen. Virtual image is
upright.
a virtual image is formed when diverging rays are extrapolated backwards and
does not form a visible projection on a screen

Real & inverted Image Virtual & upright Image

53

Image Formation

54

Robila Imran 27
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding

55

Image Formation for Convex Lens Summary

S. No. Object Position Image Position Type of Size of Use
Image Image
1 Beyond 2F Between F & 2F Real & Smaller in Camera
Inverted size
2 Between F & 2F Beyond 2F Real & Larger Projector/enlar
Inverted ged photograph

3 At 2F At 2F Real & Same Size Photocopier

Inverted
4 Between F and At infinity Virtual & Magnified Magnifying
Optical Centre Upright Glass

56

Robila Imran 28
 13

25 Which diagram shows how the light from a candle is reflected by a mirror, and shows the po
of theused
This is a teaching resource image
to formed?
give 9/6/24
lectures some of the details explained in
A B
class may not be present in these sldies
please refer to class notes for full
understanding image of image of
candle candle
candle candle

Image formation by convex lens with more than two

rays eye

eye
mirror mirror
Image formed is real, inverted and small

Ray1 is parallel to the principal axis and is refracted through F

Ray2 passes straight through the center of C the lens D
Ray3 passes through F and after refraction it goes parallel to the principal axis

candle candle

image of
57 eye
candle

image of eye
candle
Q26/M20/P22 mirror mirror

26 A converging lens can be used as a magnifying glass.

What will be the nature of the image?

A real, inverted, diminished

B real, upright, enlarged
C virtual, inverted, enlarged
D virtual, upright, enlarged D

58

Robila Imran 29
© UCLES 2020 0625/22/F/M/20 [Turn
 22 A plane mirror is fixed so that it is at an angle of 45° to a table. A ray of light, initially parallel to
the table, is incident on the mirror.

plane mirror

ray of light

This is a teaching resource used to give 9/6/24

lectures some of the details explained in 45° table

class may not be present in these sldies

Which angle does the reflected ray make with the table?
please refer to class notes for full
A 0° B 22.5° C 45° D 90°
understanding
23 An object is placed 20 cm in front of a thin converging lens. The scale drawing shows how the
lens forms a real, inverted image.

Q23/W18/P13

object

10
image

23 A student uses one eye to look at images in a plane mirror.

scale
5.0 cm
plane mirror

Which row gives the focal length of the lens and the distance of the image from the lens?

focal length distance of image

P Q of lens / cm R from lensE/ cm S T A U
X A 4.0 5.0
Y
B 5.0 4.0
C 8.0 10.0
Objects are placed on the line XY.
D 10.0 8.0

Which objects give rise to images that can be seen by the eye at E?
59
A P, Q, R, S, T and U

B Q, R, S and© T only
UCLES 2018 0625/13/O/N/18 [Turn over

C P and U only
D R and S only
Q24/S22/P22

24 An object is placed in front of a converging lens of focal length 15 cm.

Which row describes the image of the object?

distance of object
nature of the image
from lens / cm

A 40 real, upright, diminished

B 30 virtual, inverted, enlarged
C 20 real, inverted, diminished D
D 10 virtual, upright, enlarged

25 The speed of light in air is 3.0 × 108 m / s.

The critical angle for light in a transparent plastic material placed in air is 37°.

What is the speed of light in the plastic material?

60 A 1.8 × 108 m / s

B 2.4 × 108 m / s

C 3.8 × 108 m / s
Robila Imran 30
D 5.0 × 108 m / s
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding

9
Q22/S19/P22
22 A small object O is placed near a converging lens, as shown. The lens forms an image I.

I O

Which statement is correct? D

A The image I is diminished.

B The image I is inverted.

C The image I is real.

D The object O is closer to the lens than its principal focus.

23 An eclipse of the Sun happens when the Moon comes between the Earth and the Sun.
61
Which statement is correct?

A Infra-red radiation from the Sun disappears before visible light and ultra-violet radiation.
9
B Ultra-violet radiation from the Sun disappears before visible light and infra-red radiation.
7 (a) Fig. 7.1 shows the position of a converging lens, its principal axis and an object O.

C Visible light from the Sun disappears before ultra-violet radiation and infra-red radiation.
Q7/W19/P43 principal
D Infra-red radiation, ultra-violet radiation and visible light from the Sunaxis
all disappear at the
same moment.

F O F
24 A pulse of sound is produced at the bottom of a boat. The sound travels through the water and is
reflected from a shoal of fish. The sound reaches the boat again after 1.2 s. The speed of sound
in the water is 1500 m / s. lens

boat
Fig. 7.1

Each principal focus of the lens is labelled F.

On Fig. 7.1, draw a ray diagram to locate the position of the image formed by the lens.

Label the image I.shoal of fish [3]

(b) Describe the nature of the image I.

How far below the .............................................................................................................................................

bottom of the boat is the shoal of fish? [2]

(c) Images formed by lenses sometimes have coloured edges.

A 450 m B 900 m C 1800 m D 3600 m
Suggest a reason for this.

...................................................................................................................................................

............................................................................................................................................. [1]

[Total: 6]
62

© UCLES 2019 0625/21/M/J/19 [Turn over

Robila Imran 31
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding

9
Q5/S20/P41
5 The distance between the centre of a thin converging lens and each principal focus is 5.0 cm.

(a) Describe what is meant by the term principal focus for a thin converging lens.

...................................................................................................................................................

...................................................................................................................................................

............................................................................................................................................. [2]
9

5 (b)
TheThe lensbetween
distance is usedthe
as centre
a magnifying glass to produce
of a thin converging lens and an image
each I offocus
principal an object O.
is 5.0 cm.

(a) Describe what is meant by the term principal focus for a thin converging lens.
(i) Underline the terms that describe the nature of the image produced by a magnifying
glass. [2]
...................................................................................................................................................

...................................................................................................................................................
diminished enlarged inverted real same size upright virtual
............................................................................................................................................. [2]

(b) (ii)
The Fig. 5.1
lens is is aasfull-scale
used diagram
a magnifying ofproduce
glass to the lens
anand theI of
image image I. O.
an object

(i) Underline the terms that describe the nature of the image produced by a magnifying
63 glass. [2]

diminished enlarged inverted real same size upright virtual

I (ii) Fig. 5.1 is a full-scale diagram of the lens and the image I.

centre
centre of of lens
lens

1 cm
1 cm 1 cm

1 cm Fig. 5.1 (full-scale)

1. On Fig. 5.1, mark both principal focuses and label each of them F. [1]
Fig. 5.1 (full-scale)
2. By drawing on Fig. 5.1, find the position of object O and add object O to the diagram.
[3]

(iii) Using Fig. 5.1, determine the distance of object O from the centre of the lens.
1. On Fig. 5.1, mark both principal focuses and label each of them F. [1]

2. By drawing on Fig. 5.1, find the position of object O and add object O to the diagram.
distance = ......................................................... [1] [3]
64 [Total: 9]
(iii) Using Fig. 5.1, determine the distance of object O from the centre of the lens.
© UCLES 2020 0625/41/M/J/20 [Turn over

Robila Imran 32
distance = ......................................................... [1]

[Total: 9]
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding

Using lenses to correct eyesight problems

Our eyes contain converging lenses
which form an image on the retina at
the back of the eye.
Short-sightedness
A person with short sight can see
closeup objects clearly but cannot form
a clear image of distant objects. To
correct this a diverging lens is used to
make the rays from the distant object
diverge by increasing the focal length of
eye. The eye is then able to form
a focused image.

65

Long-sightedness
A person with long sight can see distant
objects clearly but cannot form a clear
image of close objects.
To correct this a converging lens is used
to make the rays converge by reducing
the focal length of eye, allowing the eye
lens to form a focused image of close
objects.

66

Robila Imran 33
 10
This is a teaching resource used to give 10 9/6/24
lectures some7 of(a)the
In details
Fig. 7.1, aexplained in projects a sharp image of an object O on to a screen.
converging lens
7 (a) In Fig. 7.1, a converging lens projects a sharp image of an object O on to a screen.
class may not be present
Complete inthe
these
pathssldies
of the two rays from the object to the screen.
please refer to class notes for full
Complete the paths of the two rays from the object to the screen.
10
converging lens
understanding converging lens screen
7 (a) In Fig. 7.1, a converging lens projects a sharp image of an object O on to a screen. screen
Complete the paths of the two rays from the object to the screen.

O converging lens
Q7/S19/P42 screen
O

O
Fig. 7.1 [2]

(b) The converging lens in (a) is replaced with a 7.1

Fig. thinner converging lens. The object O and the [2]
screen remain in the same positions as in (a). The thinner converging lens has a longer focal
length
(b) The than the converging
converging lens
lens in (a) is in (a).
replaced with a thinner converging lens. The object O and the
Fig. 7.1 [2]
screen remain in the same positions as in (a). The thinner converging lens has a longer focal
Complete
(b) The the paths lens
converging of the
in two rays
(a)lens
is from the object to the screen in Fig. 7.2.
replaced
length than the converging in (a). with a thinner converging lens. The object O and the
screen remain in the same positions as in (a). The thinner converging lens has a longer focal
thinner converging
length than lens lens in (a).
the converging
Complete the paths of the two rays from the object to the screen in Fig.screen
7.2.
Complete the paths of the two rays from the object to the screen in Fig. 7.2.
thinner converging lens
thinner converging lens screen
screen
O

O O

67
Fig. 7.2 [2]

(c) A converging lens is used as a magnifying glass.

The focal length of the lens is 10 cm. Fig. 7.2 [2]
Fig. 7.2 [2]
(i)
(c) Describe the lens
A converging position of the
is used as aobject in relation
magnifying glass.to the lens.
The focal length
(c) A converging lens isof used
the lens asisa10 cm.
magnifying glass.
...........................................................................................................................................
The focal length of the lens is 10 cm.
(i) Describe the position of the object in relation to the lens.
..................................................................................................................................... [1]
(i) Describe the position of the object in relation to the lens.
...........................................................................................................................................
(ii) Describe the position of the image in relation to the lens and the object.
..................................................................................................................................... [1]
...........................................................................................................................................
...........................................................................................................................................
(ii) Describe the position of the image in relation to the lens and the object.
..................................................................................................................................... [1]
.....................................................................................................................................
...........................................................................................................................................[1]
(ii) Describe the position of the image in relation to the lens and the object.
(iii) Give .....................................................................................................................................
three properties of the image formed by a magnifying glass. [1]
...........................................................................................................................................
...........................................................................................................................................
(iii) Give three properties of the image formed by a magnifying glass.
..................................................................................................................................... [1]
...........................................................................................................................................
...........................................................................................................................................
(iii) Give three properties of the image formed by a magnifying glass.
...........................................................................................................................................
..................................................................................................................................... [2]
..................................................................................................................................... [2]
...........................................................................................................................................
[Total: 8]
© UCLES 2019 0625/42/M/J/19 [Total: 8]
© UCLES 2019
...........................................................................................................................................
0625/42/M/J/19

..................................................................................................................................... [2]

[Total: 8]
© UCLES 2019 0625/42/M/J/19
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Robila Imran 34
This is a teaching resource used to give 9/6/24
lectures some of the details explained in
class may not be present in these sldies
please refer to class notes for full
understanding 10

5 Fig. 5.1 shows a road junction, a moving car and a stationary truck. The road has high walls on
each side.
Q5/W23/P42
10

5 Fig. 5.1 shows a road junction, a moving car and a stationary truck. The road has high walls on
each side.

truck

car
truck

Fig. 5.1
car
(a) The driver of the truck is at position X. The car moves around the corner.

On Fig. 5.1, label a point Y on the road where the truck driver first sees the car. [1]

(b) A plane mirror is placed at the road junction as shown

Fig. 5.1 in Fig. 5.2.
69
(a) The driver of the truck is at position X. The car moves around the corner.

On Fig. 5.1, label a point Y on the road where the truck driver first sees the car. [1]

(b) A plane mirror is placed at the road junction as shown in Fig. 5.2.

truck

car

truck

Fig. 5.2

Show howcarthis mirror allows the driver of the truck to see the car when it is at the position
shown in Fig. 5.2. [2]

© UCLES 2023 0625/42/O/N/23

Fig. 5.2

Show how this mirror allows the driver of the truck to see the car when it is at the position
shown in Fig. 5.2. [2]

70
© UCLES 2023 0625/42/O/N/23

Robila Imran 35
 image of an object O forms on the retina. Any effect of the cornea on the rays of light can be
ignored.
lens retina
lens retina

This is a teaching resource used to give 9/6/24

O
lectures some Oof the details explained in 11
class may not be present in these sldies (c) The truck driver wears spectacles to correct long-sightedness. Fig. 5.3 shows how a blurred
please refer to class notes for full image of an object O forms on the retina. Any effect of the cornea on the rays of light can be
ignored.
understanding cornea
cornea 11

(c) The truck driver wears spectacles to correct long-sightedness. Fig. 5.3 shows how a blurred lens retina
image of an object O forms on the retina.
Fig.Any
5.3effect of the cornea on the rays of light can be
ignored.
Fig. 5.3
On Fig. 5.4, show how long-sightedness is corrected by:
O
On Fig. 5.4, show how long-sightedness
lens is corrected by: retina
• adding a suitable lens in front of the eye
• continuing the path of the three rays of light until they meet to form an image.
• adding a suitable lens in front of the eye
• continuing
O the path of the three rays of light until they meet to form an cornea
image.
lens retina

lens retina Fig. 5.3

cornea
O On Fig. 5.4, show how long-sightedness is corrected by:

Fig. 5.3 • adding a suitable lens in front of the eye

O • continuing the path of the three rays of light until they meet to form an image.
On Fig. 5.4, show how long-sightedness is corrected by:

• adding a suitable lens in front of the eye lens retina

• continuing the path of the three rays of light until they meet to form an image.
Fig. 5.4
[4]
lens retina
O
[Total: 7]

Fig. 5.4
O
[4]

71 [Total: 7]
Fig. 5.4
[4]

Fig. 5.4 9 [Total: 7]

[4]
(c) Fig. 5.3 shows a simplified diagram of an eye with rays from a distant object and the path of
the rays inside the eye of a person with short sight. [Total: 7]
Q5/M23/P42

© UCLES 2023 0625/42/O/N/23 retina

[Turn over

lens

Fig. 5.3
© UCLES 2023 0625/42/O/N/23 © UCLES 2023 [Turn over
0625/42/O/N/23 [Turn over
On Fig. 5.4, draw an additional lens outside the eye to correct short-sightedness and show
© UCLES 2023
the path of the0625/42/O/N/23
rays inside the eye. [Turn over

Fig. 5.4
[2]

72 [Total: 10]

Robila Imran 36