chapter 7 latest-conv

Topic 7 Light, Colour And Sight

The Human Nervous System

Comparing Eye And Camera In Focusing
A Near Object

Ciliary

muscles

Eye lens becomes

thicker. Light from

Eye Focal length near
becomes shorter. object

Lens

becomes

thicker

Camera Camera lens Lens
moves
moves outwards. outwards

Light >
from >
near
object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.3 Light Dispersion
Penyebaran Cahaya

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Dispersion

Process: Light Dispersion
Characteristic Of Light

✓ Light travels in a straight line.

✓ Light is refracted towards normal when it travels from a less density
medium to a more density medium and vice-versa.

Air i

Glass i = angle of incidence

r

r r = angle of refraction

i>r

i

✓ While light consists of seven different colour of light which travel at
different velocity.

✓ Refraction of light occurs because of the velocity of light changes when
it moves from one medium to another different medium.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Dispersion

Light Dispersion

Spectrum of
visible light

✓ Dispersion of light occurs when light dispenses into seven component
colours when it enters from one medium to another different medium.

✓ Red light is refracted the least because it travels the fastest whereas
violet light is refracted the most as it travels the slowest.

ITeach – Science Form 4

Light Dispersion Topic 7 Light, Colour And Sight

Spectrum of
visible light

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Dispersion

Recombining The Colour In The Spectrum

❖ When a second identical prism is
placed inversely behind the first
prism, a beam of white light is
seen on the screen.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Dispersion

The Formation Of Rainbow

✓ Rainbow is a natural phenomenon caused by the dispersion of sunlight by
raindrops.

✓ A rainbow where sunlight undergoes two refraction and one total internal
reflection in raindrops.

✓ Red light moves fastest, refracted least
✓ violet light move slowest, refracted most

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.4 Light Scattering
Penyerakan Cahaya

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Scattering

Light Scattering

Atmosphere consists of gas particles water vapour and dust
particles

Light striking on the particles and get absorbed and reradiated to
different direction.

Red Orange Yellow Green Blue Indigo Violet

Longest Wavelength Shortest

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Scattering

Light Scattering In Natural Phenomena

❖ During noon time, sunlight travels through thin atmosphere layer.
❖ Blue, indigo and violet light are scattered more than other light colour by

atmosphere particles. (because wavelength of blue is shorter than red)

Blue sky from Blue sky is scattered
scattered light by air molecules or
dust

Orange And Red
Light Continue To

Travel

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

Light Scattering

❖ During down or sunset, the sun appears red.
❖ Sunlight travels through very thick atmospheric layers.
❖ Blue, indigo and violet lights have been scattered away.
❖ Only red and orange light reach our eyes.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.5 The Addition And Subtraction Of Coloured Light
Penambahan Dan Penolakan Warna

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Colour

Primary colour Secondary colour
• Cannot be produced by mixing • Can be obtained by adding any

other colour. two of the primary colours.

Example : Red, Green and Blue Example : Yellow, Magenta and Cyan

Example : Addition of two primary colours can obtain the secondary colour.

Addition of 3 primary colours will produce

Red + Green = Y white light

Yellow Red

Red + Blue = M Magenta

Green Blue White
light

Green + Blue = C

ITeach – Science Form 4 Cyan

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Complementary colour (any two colours Colour obtained
which mixed to produce white) White

Yellow + Blue

Magenta + Green White

Cyan + Red White

SecoRneddary+ Green = Yellow Red
Colour P=rimaryMColour
=C Magenta
Red + Blue
Green Blue White
Green + Blue light

ITeach – Science Form 4 Cyan

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Subtraction Of Coloured Light

✓ The absorption of coloured lights by a filter is known as
the subtraction coloured lights.

✓ Filter is a transparent material that allows only certain
coloured light to pass through it. All the other colours are
absorbed.

colour colour
pass pass
through through

Red filter Green filter Blue filter

✓ A secondary coloured filter (yellow, magenta and cyan) allow its own colour and or
component colour to pass through it.

White colour White colour White pass
light pass light pass light through
through through
Yellow filter Cyan filter Magenta filter

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Subtraction Of Coloured Light

Colour that pass through:
Colour that formed on the screen:

✓ A primary coloured filter (red, green and blue) can only allow its own colour
to pass through it, all the other colours are absorbed.

White colour White colour White colour
light pass light pass light pass
through through through

Red filter Green filter Blue filter

✓ A secondary coloured filter (yellow, magenta and cyan) allow its own colour
and or component colour to pass through it.

White colour White colour White pass
light pass light pass light through
through through
Yellow filter Cyan filter Magenta filter

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Subtraction Of Coloured Light

✓ A primary coloured filter (red, green and blue) can only
allow its own colour to pass through it, all the other
colours are absorbed.

White Red White Green White Blue
light colour light colour light colour
pass pass pass
through through through

Red filter Green filter Blue filter

✓ A secondary coloured filter (yellow, magenta and cyan)

allow its own colour and or component colour to pass

through itR.ed,

yellow Green Red
Blue Blue
White and green White colour White pass
light pass light through
light colour through
Cyan filter Magenta filter
pass

through
Yellow filter

CC

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Subtraction Of Coloured Light By More Than 2 Filters

When two or more filters are hold together, only the colour common to the
filter can pass through them

White White
light light

Yellow Cyan Red Magenta
filter filter filter filter

White White
light light

Cyan Red Red Yellow
filter filter filter filter

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Addition And Subtraction Of Coloured Light

Subtraction Of Coloured Light By More Than 2 Filters

When two or more filters are hold together, only the colour common to the
filter can pass through them

White White Red
light light
Green

Yellow Cyan Red Magenta
filter filter filter filter

White No light White Red
light light light

Cyan Red Red Yellow
filter filter filter filter

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.6 The Appearance Of Coloured Object
Penglihatan Objek Berwarna

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Appearance Of Primary Coloured Object

Colour of an object as we see depend on

➢ The colour of the light ➢ The colour of the light that is

that shine on the object. reflected by the object.

✓ A primary coloured object will reflect its own colour and

absorbs (subtract) all other colour.

Red

White light Red object reflects its own colour
and absorbs all other colour
light

E Red Object

X

A
M White
light
P Green Object
L

E

White
light

BlueObject

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Appearance Of Primary Coloured
Object

Colour of an object as we see depend on

➢ The colour of the light ➢ The colour of the light that
that shine on the object. is reflected by the object.

✓ A primary coloured object will reflect its own colour and
absorbs (subtract) all other colour.

Red

White light Red object reflects its own colour
and absorbs all other colour
light
Green object reflects its own colour
E Red Object and absorbs all other colour.

X Green Blue object reflects its own colour
A light and absorbs all other colour.
M White
light
P Green Object
L

E Blue

White light

light
BlueObject

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Appearance Of Coloured Object

The Appearance Of Secondary Coloured Object

Secondary coloured object will reflect It absorbs (subtracts) all the colour.
its own colour and the colours that
form it.

White Red light Object appears Yellow
light Yellow light

Green light

Yellow Object Yellow object reflects its own colour, red and green
that form it. It absorbs (subtract) all other colour.

E White Object appears
X light Object appears
A
M
P Magenta Object
L
E White

light

Cyan Object

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Appearance Of Secondary Coloured Object

Secondary coloured object will reflect It absorbs (subtracts) all the
its own colour and the colours that colour.
form it.

White Red light Object appears
light Yellow light Yellow

Green light

Yellow object reflects its own colour, red and

Yellow Object green that form it. It absorbs (subtract) all

other colour.
Red light
E White Magenta light Object appears
X light Blue light Magenta

A Magenta object reflects it own colour, red and
Magenta Object blue that form it. It absorbs (subtract) all other
M
P Green lcigohlot ur.
Cyan light
L White Object appears
E light Blue light Cyan

Cyan Object Cyan object reflects its own colour, green and
blue that form it. It absorbs (subtract) all other
colour.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Appearance Of Coloured Object

The Principle The Subtraction Of Light And Seeing Coloured Object

A white object reflects all colour of light

White Object appear
light

White Object

Green Object appear
light

White Object

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Principle The Subtraction Of Light And Seeing Coloured
Object

A white object reflects all colour of light

White White
light light

Object appear white

White Object

Green Green Object appear the same
light light colour as the light that
shines on it

White Object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Appearance Of Coloured Object

The Principle The Subtraction Of Light And Seeing Coloured Object

A black object absorbs all colour of light and
does not reflect any coloured light.

White
light

Black Object

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Principle The Subtraction Of Light And Seeing Coloured
Object

A black object absorbs all colour of light and
does not reflect any coloured light.

White No light is reflected
light

Black Object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Appearance Of Coloured Object

The Principle Of The Subtraction Of Light And Seeing Coloured Object

How a primary colour object appear if it is shone with different
coloured lights?

• Primary colour object reflects its own colour.

Light shine on the Light shine on the Light shine on the
object is same as the object is a different object is a secondary
primary coloured light
object coloured light

Red Blue Yellow
light light light

Red Object Red Object Red Object
Object appears Object appears Object appears

ITeach – Science Form 4

Topic 7 Light, Colour A

The Appearance Of Coloured Object

The Principle Of The Subtraction Of Light And Seeing Coloured
Object

How a primary colour object appear if it is shone with different
coloured lights?

• Primary colour object reflects its own colour.

Light shine on the Light shine on the Light shine on the
object is same as the object is a secondary
object is a different
object coloured light
primary coloured

Red Red Blue light Yellow Red
light light light light light
No light
is

reflected

Red Object Red Object Red Object
Object appears red
Object appears black Object appears red
as yellow is formed
ITeach – Science Form 4 from red and green.
Green light is
absorbed. Red light
is reflected

Topic 7 Light, Colour And Sight

The Appearance Of Coloured Object

How A Secondary Coloured Object Appear When
Shone With Different Coloured Light

A secondary coloured object reflects its own colour and its component colour.

Shine with same coloured Shine with the component coloured light which forms it
light
Red Green
Yellow light light
light

Yellow Object Yellow Object Yellow Object
Object appears Object appears Object appears

Shine with primary coloured light Shine with other secondary coloured light

which is not its component Magenta

colour light Cyan

Blue light

light Yellow Object Yellow Object

Yellow Object Because Because

Object appears

ITeach – Science Form 4

Topic 7 Light, Colour And
The Appearance Of Coloured Object

How A Secondary Coloured Object Appear When
Shone With Different Coloured Light

A secondary coloured object reflects its own colour and its component colour.

Shine with same Red Green Green
coloured light Yellow Red light light light
light light
Yellow
light

Yellow Object Yellow Object Yellow Object
Object appears
red

Object appears yellow because yellow object Object appears green

reflects red, yellow and

Shine with primary coloured green.
light which is not its Magenta

component colour light Red Cyan Green
light light light
Blue No light is
Yellow Object
light reflected Yellow Object

Yellow Object Because magenta Because cyan colour

Object appears black colour light is formed light is formed by blue
because yellow object by red and blue light. and green light. Yellow
ITeacahbs–oSrbcsiebnlcuee Form 4 Yellow object reflects object reflects green

Rod cells and cone cells in eye

Topic 7 Light, Colour A

The Appearance Of Coloured Object

Functions Of Rod And Cone Cells In The Eye
➢ The retina in human consists of millions of light sensitive cells

called receptors.

➢ The receptor are divided to rod and cone cells.

Rod cells

✓ Sensitive to low intensity of light, shades of grey and give black
and white vision.

✓ function well in dim light.

Cone cells

✓ Sensitive to coloured lights.

✓ 3 types with each sensitive to red, blue and green light
respectively.

✓ Light from magenta object enters the eye, red and blue cone cells
are stimulated. Brain recognizes red and blue ones are stimulated
at the same time. Brain interpret the colour of object as magenta.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.7 The Effect Of Mixing Pigment
Kesan Pencampuran Pigmen

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Effect Of Mixing Pigment

The Effect Of Mixing Pigment

✓ Pigment can be obtained naturally from plants, animals and soil or
synthetic by extracting from coal or oil and make an artificial ones.

✓ Primary colours of pigment are red, yellow
and blue.

✓ The mixing of 2 primary colours of
pigment produces secondary colour
pigment which are violet, orange and
green.

✓ Mixing of 3 primary colours of pigment
produces black.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Effect Of Mixing Pigment

The Effect Of Mixing Pigment

Merah + Biru = Ungu Mak Beli Udang
Kuning + Biru = Hijau Kakak Beli Halia
Merah + Kuning = Jingga Makan Kenyang Joget
Merah + Biru + Kuning = Hitam Mak Beli Kuali Hitam

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Effect Of Mixing Pigment

Compare And Contrast The Mixing Of Pigments With The
Addition Of Coloured Lights

Mixing of pigments Addition of coloured lights

Green Yellow Orange Yellow Red Magenta

Blue Red Green Blue

Violet Cyan

Similarity
Each has it own primary and secondary colour

Mixing of pigments Differences Addition of coloured
lights

Yellow, red and blue Primary colour Blue, red and green
Green, violet and Yellow, cyan and
orange Secondary magenta
Addition or mixing of
Black White
3 primary colours

Colour subtraction Process Colour addition

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Effect Of Mixing Pigment

The Action Of Light On Pigment

➢ Colours formed by mixing of pigment is by colour subtraction
process.

➢ Example : magenta + cyan ----→ blue

White White
light
Wlighhten two coloured pigments
White
are mixed, the resWuhltitieng light White
colour iBslutehe:- light Yellow light

+ + Red

WChoitelour reflected by boGrtehenthe Violet
pligihgtments.

Yellow

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.8 The Important Of Colour In Daily Life
Kepentingan Warna Dalam Kehidupan Harian

ITeach – Science Form 4

Topic 7 Light, Colou

The Important Of Colours In Daily Life

The Importance Of Colour To Human

To mark and convey (deliver) meaning.

To make environment brighter and more attractive

Topic 7 Light, Colour A

The Important Of Colours In Daily Life

Uses Of Colour In Daily Life

✓ Traffic lights ✓ Electrical wiring
Red, Yellow and Green to Brown, Blue and Yellow with

control the flow of traffic. green stripe used for electrical

wiring.

Red - Stop

Yellow - Prepare to stop
Green - Go

✓ Colour television ✓ Resister colour code to
Colour television screen is Different colour stripes
made up of millions of tiny show the resistance value.
phosphor dots with red, blue
and green colour.

ITeach – Science Form 4

Topic 7 Light, Colou

The Important Of Colours In Daily Life

To The Importance Of Colour To
Animals Animals - Reproduction

Reproduction

Male animals are the one which have bright
and colourful outlook to attract the female.

Topic 7 Light, Colou

The Important Of Colours In Daily Life

To The Importance Of Colour To
Animals Animals - Camouflage

Camouflage

Animals use colours to hide themselves
from their enemies

Leaf and Zebra hiding Chameleons
stick among
insect bushes

Topic 7 Light, Colou

The Important Of Colours In Daily Life

To The Importance Of Colour To
Animals Animals – As A Warning

As A Warning

Animals have very bright colour or patterns
on their bodies to frighten their enemies.
Brightly-coloured animals are usually
poisonous animals.

Topic 7 Light, Colou

The Important Of Colours In Daily Life

The Importance Of Colour To
Plants

✓ Plants produce brightly- ✓ Some plants produce
coloured flowers to colourful fruits to attract
attract birds insects or animals and hence help
other small animals to to disperse the seeds.
help in pollination.