light

(ii) Calculate the distance of the image of the (d) A leaf blown by a strong wind covered the
writing from the optical centre of the upper portion ot the convex lens X.What
lens. will happen to the size and brightness of the
image?
[ 2 marks ] ……………………………………………....
(iii) In the space below sketch a ray ........................................................................
[ 2 marks ]
diagram to show how the image is
formed. (e) The convex lens X and another convex lens
Y of focal length 50 cm are used to construct
[ 3 marks ] a simple astronomical telescope.
54 Diagram 54 shows an object, O with height (i) Which lens is suitable to be
objective lens and eyepiece?
2 cm placed in front of a convex lens, X.The
focal length of the convex lens X is 10 cm. Objective lens:
………………………………

Eyepiece:
………………………………

[ 1 mark ]
(ii) Give one reason to your answer

in (d) (i).
………………………………..................

[ 1 mark ]
(iii)What is the distance between lens X and

lens Y , when the telescope at a normal
adjusment.
..................................................................

[ 1 mark ]
55 Diagram 55 shows an object is placed in front

of a concave lens. F is the focal point of the
lens.

Diagram 54 Diagram 55
(a) What is meant by the focal point of a lens.
(a) In Diagram 54 ,complete the ray diagram to
show how an image formed. ........................................................................
[ 3 marks ] ........................................................................

(b) State the characteristics of the image [ 1 mark ]
formed. (b) In Diagram 55 ,complete the ray diagram to
……………………………………................
[ 1 mark ] show how an image formed.
[ 3 marks ]
(c) When the object is placed at a distance 15
cm from the lens X, calculate: (c) When the object is placed at a distance 15
cm from the lens , a virtual image at a
(i) the image distance. distance 5 cm from the lens is formed.
Calculate the focal length of the lens.
[ 2 marks ]
[ 2 marks ]
(ii) linear magnification. (d) What happen to the image when a screen is

placed behind the lens.
........................................................................

[ 1 mark ]

[ 2 marks ]

51

56 (a) Diagram 56 shows a magnifying glass used Type of lenses Object Distance
by long - sighted person to read a book. distance, uo between
Arran from objective
Diagran 56 gement objective lens and
(i) What type of lens is used for the lens eyepiece
lens, d
magnifying glass.
................................................................. Objective lens is

( 1 mark ) J convex lens uo<fo d < (fo+fe)
(ii) Give the reason for your answer in (a)(i). and eyepiece is

................................................................. concave lens
( 1 mark )
Objective len is
(iii) State the characteristics of the image
formed. K concave lens uo = fo d = (fo+fe)
…………………………………….......... and eyepiece is
[ 1 mark ]
convex lens
(b) In the space below sketch a ray
diagram to show how the image is Both are convex
formed. L lens for objective fo <uo<2fo d > (fo+fe)

[ 3 marks ] lens and eyepiece
(c) The magnifying glass also known as a
Table 56
simple microscope but a compound . Based on Table 56, state the suitable
compound microscope contains an objective arrangement in order to build a simple
lens and an eyepiece lens. The focal length compound microscope. Give one reason for the
of the objective lens is fo and the focal length suitable arrangement.
of eyepiece lens is fe. (i) Type of lenses:
Table 56 shows three arrangement of a
compund microscope. ........................................................................
Reason :
………………………………........................

[2 marks]
(ii) Object distance, u0:

........................................................................
Reason :
………………………………........................

[2 marks]
(ii) Distance, d:

........................................................................
Reason :
………………………………........................

[2 marks]
(d)Based on the answer in (c), choose the most

suitable arrangement for a sinple compound
microscope.
…………………………………………....................

[1 mark]
57 Diagram 57 shows a ray diagram of the

convex lens with a focal length of 25 mm in a
camera of smartphone in which the minimum
distance between the optical centre of the lens
and the sensor is equal to the focal length of the
lens.

Diagram 57

52

(a) One of the characteristic of the image (b) Diagram 58.3 shows the ray diagram of
formed by the lens is inverted. a compound microscope.
(i) State two others characteristics of the
image formed. Diagram 58.3
........................................................................ Based on Diagram 58.3
........................................................................
[2 marks] (i) Explain the working principle of the
(ii) The image that appears is vertical even microscope.
though the image is actually inverted. [4 marks]
State how the image was made
upright? (ii) Suggest and explain how to modify the
.................................................................. microscope to be a telescope, based on
[1 mark] the following aspect:
-Lenses use to produce the largest and
(b) (i) State the normal adjusment of the lens in the brightest image
the camera. -The position of the lenses
.................................................................. -Handling the telescope
[1 mark] [ 10 marks ]

(ii) What is the minimum thickness of the 59 Diagram 59.1 and Diagram 59.2 show the light
smartphone. rays from a same person but in different object
................................................................. distance , passing through the two identical
cameras with a lens.
(c) When h = 5 mm and u = 80 cm , calculate
H.

[ 2 marks ]
58 Diagram 58.1 and Diagram 58.2 show the

parallel rays directed towards the convex
lenses J and K. Both the lenses produce real
images. F is the focal point for each lens.

Diagram 59.1

Diagram 58.1

Diagram 58.2 Diagram 59.2

(a) (i) What is meant by focal length? (a) (i) What is meant by a lens?
[1 mark] [1 mark]

(ii) Using Diagram 58.1 and Diagram 58.2, (ii) Using diagram 59.1 and 59.2 , compare
compare the rays of light directed to the the object distance , the height of the
lens the thickness of the lenses and the image and the focal length of the lens.
effects it has on the refracted rays to make a State the relationship between
deduction regarding the relationship between - the object distance and the height of
the thickness of the lenses and their focal the image
length. - the object distance and the linear
[5 marks] magnification.
[5 marks]
53
(b) Diagram 59.3 shows a tool used to repair
watches.

61 Diagram 61 shows two convex lenses with
its envelopes respectively.

Diagram 59.3 Diagram 61
Explain how the tool works.
Based on the information and observation-
[4 marks] (a) Stale one suitable inference.
(c) You are given the opportunity to choose two
[1 mark]
lenses to make a compound microscope (b) State one suitable hypothesis.
Explain your answer based on the following
aspects : [1 mark]
- Charactristics of lenses used (c) With the use of apparatus such as a convex
- The arrangement of the lenses
lens, screen and other suitable apparatus,
[10 marks] describe one experiment to investigate the
60 Diagram 60.1 shows the light from light bulb is hypothesis stated in (b).
In your description, state clearly the
directed to dark box (object) and a beaker filled following:
of water. The position of white screen is
adjusted until a sharp image formed on the (i) The aim of the experiment.
screen. (ii) The variables in the experiment.
Diagram 60.2 shows the same procedure is (iii) The list of apparatus and materials.
repeated but with different distance between (iv) The arrangement of the apparatus.
dark box and the beaker. (v) The procedure of the experiment which

Diagram 60.1 should include one method of
controlling the manipulated variable
Diagram 60.2 and one method of measuring the
Based on the information and observation- responding variable.
(a) Stale one suitable inference. (vi) The way to tabulate the data.
(vii) The way to analyse the data.
[1 mark]
(b) State one suitable hypothesis. [10 marks]

[1 mark]
(c) With the use of apparatus such as a convex

lens, screen and other suitable apparatus,
describe one experiment to investigate the
hypothesis stated in (b).
In your description, state clearly the
following:
(i) The aim of the experiment.
(ii) The variables in the experiment.
(iii) The list of apparatus and materials.
(iv) The arrangement of the apparatus.
(v) The procedure of the experiment which

should include one method of
controlling the manipulated variable
and one method of measuring the
responding variable.
(vi) The way to tabulate the data.
(vii) The way to analyse the data.

[10 marks]

54

LESSON 4 – FORMATION OF 4.3 Common terminology of reflection of light
IMAGE BY SPHERICAL on a spherical mirror
MIRROR Concave mirror :

4.1.Introduction Conve mirror :
A spherical mirror is an opaque material which
consists of smooth, shiny and curved surface. Pole of mirror , P
For example , the front and back surfaces of steel The centre point on the spherical mirror
spoons can act as concave mirrors and convex Centre of curvature , C
mirrors, respectively The centre of sphere that produced the concave or
Images formed by mirrors due to the phenomenon convex mirror
of reflection of light. Radius of curvature, r
Rays of light from objects at infinity ( distant The distance between the pole, P and the
objects) are parallel rays. centre of curvature, C.
There are two types of spherical mirror i.e.concave Principal axis ,PFC :
mirror and convex mirror.. A line which passes
through the centre of curvature ,C and the pole of a
4.2.The comparison of the field of view between curved mirror, P
plane mirror , convex mirror and concave Focal point , F
mirror. A point throughwhich all rays traveling parallel to
the principal axis converge to or appear to diverge
C: Centre of curvature from after reflection by the mirror.
Angle of incidence,i = angle of reflection,r Focal length , f :
Field of view convex mirror > plane mirror > The distance between the principal focus ,F and the
concave mirror. pole of the curved mirror, P.
Object distance , u
Distance of the object from the pole of the mirror,P
Image distance , v
Distance of the image from the pole of the mirror,P

55

4.4 Relationship between f and r Ray 3:

r = 2f

4.5 Relationship curvature of mirror and f

The more curved the mirror , the shorter its focal
length, f.

4.6 Characteristics of image formed by spherical The method to complete ray diagram for convex
mirror by using ray diagrams. mirror and concave mirror

The main ray of light in drawing a ray diagram 1.Draw Ray I from the top of object.
are: 2.Draw Ray 2 or Ray 3 from the top of the
object.
Ray 1 : 3.Extrapolate Ray1 and Ray2 or Ray 3
until intersect each other.
4.Draw image at the intersection point.
5.Draw arrow from object to the image

Example 1

Complete the following ray diagram and state the
characteristics of image formed

Ray 2 : Solution

or

56

Example 2 (c) f < u < 2f or f < u < r ( Object O is between F
and C.
Complete the following ray diagram and state the
characteristics of image formed

Solution (d)u = 2f or u = r ( Object ,O is at C)
or

Example 3 (e) u > 2f or u > r ( Object, O is beyond C )

(a) Complete the following ray diagrams for
concave mirror
(b) State the characteristics of image formed
(c)Complete the table below

(a) u < f ( Object between F and P )

(f) u = ∞ ( Object ,O very far from the lens)

(b) u = f ( Object, O is at F )

57

The distance object, u Characteristics of image (d) u = 2f or u = r ( Object ,O is at C)
u <f
u =f Characteristics of image :
f < u < 2f ..................................................................................
u = 2f ..................................................................................
u > 2f (e) u > 2f or u > r ( Object, O is beyond C )
u=∞
Solution

(a) u < f ( Object between F and P )

Characteristics of image :
..................................................................................
..................................................................................

(b) u = f ( Object, O is at F )

Characteristics of image :

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

..................................................................................
F u = ∞ ( Object ,O very far from the lens)

Characteristics of image : Characteristics of image :
.................................................................................. ..................................................................................
.................................................................................. ..................................................................................
(c) f < u < 2f or f < u < r ( Object O is between F
and C. The distance object, u Characteristics of image
u <f
Characteristics of image : u =f
.................................................................................. f < u < 2f
.................................................................................. u = 2f
u > 2f
u=∞

58

Example 4 Solution
(a) u < f ( Object between F and P )
(a) Complete the following ray diagrams for
convex mirror
(b) State the characteristics of image formed
(c)Complete the table below

(a) u < f ( Object between F and P )

(b) f < u < 2f or f < u < r ( Object O is between F Characteristics of image :
and C) ..................................................................................
...................................................................................

(b) f < u < 2f or f < u < r ( Object O is between F
and C)

The object distance, u Characteristics of image Characteristics of image :
u <f ..................................................................................
f <u < 2f ................................................................................

The object distance, u Characteristics of image
u <f
f <u < 2f

59

4.7 Uses of the concave mirror and convex Example 6
mirror Complete ray diagram for the concave parabolic
mirror in a torchlight as shown below and state the
4.7.1Concave mirror for shaving mirror ,a characteristics of the final image.

make-up mirror and for dentist mirror Solution

Function To magnify image of an

object

Structure Used a concave mirror

with a large radius of

curvature.

Normal adjusment u<f

Ray diagram ?

Characteris tics of final ?

image

Example 5

Complete ray diagram for the dentist mirror
as shown below and state the characteristics
of the final image.

Solution

4.7.3 Convex mirror at sharp corner of a
road or hung in a supermarkets.

4.7.2Reflector of in torch light and in car’s Function To produced upright and
headlamp ( concave parabolic mirror) diminished image and
Structure widen the field of view
Function To produce parallel ray Normal adjusment Convex mirror with a
of light ( at infinity) large diameter.
Structure Concave parabolic Ray diagram The mirror is placed at
mirror is used. Characteris tics of high place and the
Normal adjusment u =f final image object is located in field
Ray diagram ? of view of the mirror
Characteris tics of ? ?
final image ?

60

Example 7 Solution
(a)
(a) Complete ray diagram for a convex mirror
in Diagram (a) and state the characteristics
of the final image

(b) Complete ray diagram in Diagram (b) to
show the field view of a convex mirror.

(b)

Diagram (a)

Diagram (b)

61

TUTORIAL 4 A1 B2
C3 D4
1 The image produced by a miror is caused by 6 Which diagram shows the correct reflection of
the light from a convex mirror?
[F is the focal point ; C is centre of
A total internal reflection of light curvature]
B diffraction of light
C refraction of light 7 Which ray diagram for a concave mirror is
D reflection of light drawn correctly?
[C = centre of curvature of mirror, F = focal
2 A mirror with reflecting surface curved point of mirror]
outwards is called

A Curved mirror
B Parabolic mirror
C Concave mirror
D Convex mirror

3 The centre of sphere of which the reflecting
surface of a spherical mirror is a part is called

A Pole of mirror
B Focal point of mirror
C Optical centre of mirror
D Centre of curvature of mirror

4 Diagram shows the parallel rays of light are
reflected by a concave mirror.

Based on diagram what is the radius of
curvature of the concave mirror.

A 2L BL
CL DL

2 4

5 The diagram shows four light rays A, B,
C and D from an object, O and is reflected by a
concave mirror to form an image I. Which of
the light ray is not correct?

62

8 Diagram shows an object placed in front of a 11 Diagram shows a candle placed in front of a
concave mirror. The distance of the object is concave mirror of focal length, f.
less than the focal length,f, of the mirror.

What are the characteristics of the image The image formed is
formed?
A Real, inverted, magnified A real, upright and magnified
B Real, inverted, diminished B real, inverted and diminished
C Virtual, upright, magnified C real, inverted and magnified
D Virtual, inverted, diminished D virtual, upright and diminished
9 Diagram shows an object placed on the focal
point , F of a concave mirror 12 An object is placed at a distance 18 cm from a
concave mirror of focal length 10 cm. What is
The reflected rays are the characteristics of the image formed?
A parallel
B diverged A real , upright and diminished
C converged B real , inverted and magnified
D converged then diverged C virtual , inverted and magnified
10 Diagram shows an object placed on the centre D virtual , upright and diminished
of curvature, C of a concave mirror
13 A concave mirror has a focal length 15 cm. The
Which of the following image is formed? image formed by the mirror is virtual, upright
and magnified. What is the object distance?

A 8 cm B 15 cm
C 20 cm D 30 cm

14 An object of height 6 cm is placed at a
distance 30 cm in front of a concave mirror of
focal length 15 cm.
What is the height of the image formed?

A 3 cm B 6 cm
B 12 cm D 24 cm

15 A parallel rays of light from distant object is
reflected 20 cm in front of a concave mirror.
When a candle is placed at a distance 45 cm
from the concave mirror , what are the
characteristics of the image of candle formed

A magnified , virtual and inverted
B magnified , real, and upright
C diminished ,virtual and upright
D diminished, real and inverted

16 The image formed by a convex mirror always

A magnified , virtual and inverted
B magnified , real, and upright
C diminished ,virtual and upright
D diminished, real and inverted

63

17 Diagram shows an object is placed in front of The light bulb in the torch light is positioned at
a convex mirror. the focal point of the mirror so that
[ C is the centre of curvature ].
A light is reflected to focal point
B light is reflected to all directions
C light is reflected as parallel beam
D light bulb is reflected and spread out

21 Diagram 21 shows image of a woman in a
spoon when she holds the spoon.

Image of the object formed at

AI B II
C III D IV

18 Which of the following is the application of a
convex mirror except

19 Which of the following is the right reason for Diagram 21
replacing a plane mirror are used as rear- view
mirrors in motor vehicles with a convex (a) Tick (√) the correct answer in the box
mirror ? provided

A To shine the object The spoon acts as a
B To widen the field of view
C To produce a brighter image concave mirror
D To produce a sharper image
convex mirror
20 Diagram shows of a parabolic mirror in a torch
.light [ 1 mark ]
(b) State the characteristics of the image

formed
..................................................................
..................................................................

[ 1 mark ]
(c) On the space below, draw a ray diagram

to show how the image of the woman
formed by the spoon.

[ 3 marks ]

64

22 Diagram 22 shows a curved mirror used as a 23 Diagram 23.1 shows two cars P and Q, moving
makeup mirror. in opposite directions, through a sharp bend. A
mirror is placed on the X.

Diagram 22 Diagram 23.1

(a) Based on Diagram 22 (a) Diagram 23.2 shows an incomplete ray
diagram when a plane mirror is placed in the
(i) state the type of mirror is used. X position.
…………………………........................
[1 mark]

(ii) state one advantage the mirror is used
compare to the plane mirror.
………………………………………......
[1 mark]

(b) On the space below, draw a ray diagram
to show how the image formed by the
makeup mirror.

[3 marks] Diagram 23..2

(ii) State the characteristics of the image (i) Complete the ray diagram in Diagram
23.2
formed. [2 marks]
……………………………………..........
(ii) State the light phenomenon involved in
[1 mark] (a) (i).
………………………………………......
(c) (i) What happen to the size of the image [1 mark]

when the curvature of the is increased. (iii) Based on your answer in (a) (i), state the
………………………………….............. problem faced by driver P.
………………………………………......
[1 mark] ………………………………………......
[1 mark]
(ii) Give the reason for your answer in
(b) Diagram 23.3 shows an incomplete ray
(c)(i). diagram when a curved mirror is positioned
………………………………….............. to replace the plane mirror in Diagram 23.2.
The curve miior is used to solve the
[1 mark] problem in (a) (iii).

65

Diagram 23.3 (a) Name the light phenomenon that is
involved to form the image by the
(i) Name the curved mirror. mirror.
…..…………………………………........ ………………………………………......
[1 mark]
[1 mark]
(ii) Complete the ray diagram in Diagram (b) Using the information in the table,
determine the focal length of the mirror
23.3 M.
…………………………………………..
[2 marks] [1 mark]

(iii) Based on your answer in b (ii), how can (c) Give the reason for your answer in (b).
………………………………………......
the curved mirror solve the problem in [1 mark]

(a) (iii)? (d) Complete Table 24
…. …………………………………........ [2 marks]
……………………………………..........
(e) An object is placed at a distance 35 cm
[1 mark] from the concave mirror M.
(i) Draw a ray diagram in the space
(c) The image characteristics produced by the below to show the formation of the
image.
curved mirror in Figure 23.3 are diminished,
[3 marks]
virtual and upright
(ii) What is the characteristics of the
(i) What happens to the characteristic of the image?
……………………………………....
image as the focal length of the curved [1 mark]

mirror increases? (iii)What is the characteristics of the
………………………………………...... image when the concave mirror M is
replaced by a convex mirror of focal
[1 mark] length same as the mirror M.
……………………………………....
(ii) Give the reason for your answer in [1 mark]

(c)(i).
………………………………………......

[1 mark]

24 An object is placed at a distance ,u from a
concave mirror, M. Table 24 shows the
characteristics of image , when the distance u is
varied.

Object Characteristics of image
distance,
u ( cm) Diminished ,inverted,real
10 ,formed at 20 cm in front of
20 the mirror
30 Table 24
40
Infinity

66

25 Diagram 25.1 and Diagram 25.2 show the ray (i) Where should the receiver be placed to
diagrams of a light bulb is placed at two obtain the strongest signal?
different distances in front of a concave mirror. ..................................................................
[1 mark]

(ii) Give one reason for your answer in
(d)(i).
..................................................................
[1 mark]

26 Diagram 26.1 and Diagram 26.2 show the
rays of light directed toward the curved
mirrors, J and K. CP is the radius of curvature,
and F is the focal point of the mirrors.

(a) What is the characteristic of the image Diagram 26.1 Diagram 26.2
formed in Diagram 25.1 ?
Tick (√) the correct answer in the box (a) (i) What is meant by focal length of a
provided. curved mirror?
[ 1 mark ]
real
(ii) Using Diagram 26.1 and Diagram 26.2 ,
virtual compare the type of mirror , the rays of
[ 1 mark ] light directed to the mirror, the curvature
of the mirrors and their focal lengths.
(b) Observed Diagram 25.1 and Diagram Hence relate the curvature of the mirrors
25.2. and the focal lengths.
(i) Compare the object distance. [ 5 marks ]
..................................................................
[1 mark] (b) Diagram 26.3 shows the image of a
(ii) Compare the image distance. patient’s teeth seen in a mirror used by a
.................................................................. dentist.
[1 mark]
(iii) Compare the size of the image. Diagram 26.3
..................................................................
[1 mark] Explain how the mirror produced image of
the teeth?
(c) Based on the answer in (b)
(i) state the relationship between object [ 4 marks ]
distance and the image distance. (c) You are required to design a make-up
.................................................................
[1 mark] mirror. The make-up mirror that is included
(ii) state the relationship between object with other items in a handbag The make-up
distance and the size of the image. mirror can be used during the day or night.
.................................................................. Explain your answer based on the following
[1 mark] aspects :
- Charactristics of mirror used
(d) Diagram 25.3 shows a parabolic dish that is - The casing of the make-up mirror
used to receive signals from a satellite - Extra feature of the make-up mirror
television station.
[10 marks]

Diagram 25.3

67

68