chapter 7 latest-conv

Topic 7 Light, Colour And Sight

7.1 The Formation Of Images By Plane Mirrors And Lenses
Pembentukan Imej Oleh Cermin Satah Dan Kanta

ITeach – Science Form 4

Topic 7 Light, Colou
The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Plane Mirror

Characteristic Image Formed By
Plane Mirrors

Laterally inverted
• Right side and left side are interchanged
Virtual
• Images cannot be displayed on a screen
Upright
• Images stand upwards as the object
Same size as the object
• No change from the size of object
Same distance of the object and the image from the
mirror

The characteristics of an image
formed by a plane mirror:

1. Virtual ( not real)- not formed on the
screen

Real image

2. Upright
(straight)

3. Same size as the object

4. Laterally inverted

➢ The letter and
the number
are inverted
laterally.

➢ Turns right
into left / left
into right

5. Image distance and object distance from the
plane mirror are the same.

Image formed by a plane mirror

Image formed by a plane mirror

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Topic 7 Light, CCohlaoputreAr n5dLSigihgtht

TUhnedFeorsrmtaantdioinngOLfeInmsaegse Plane Mirrors And Lenses

Image Formed By Convex And Concave Lenses

Type Of Lenses

Convex lens Concave lens

Parallel rays of light passing Parallel rays of light passing
through a convex lens through a concave lens

Parallel Principal F
ray axis
of O Principal F O
light axis

f The rays of light fare diverged from
The rays light are converged and the focal point (F)
meet at a point, called focal point (F)

ITeach – PShciyesnicse Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Optical terms

Optical terms Symbols

Optical centre O

Principal axis

Focal Point / F
Principal focus f
u
Focal length v

Object Distance

Image Distance

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Steps To Take To Draw A Ray Diagram For A Convex Lens

Object F 2F Principal
2F F O axis

A ray of light passes through the optical centre of the lens is undeviated.

A ray of light parallel to the principal axis is refracted and passes
through the principal focus, F.
A ray of light which passes through F is refracted parallel to the
principal axis.

The point of intersection of the rays is a point on the image.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Steps To Take To Draw A Ray Diagram For A Convex Lens

Object Image Principal
2F F O F 2F axis

A ray of light passes through the optical centre of the lens is undeviated.

A ray of light parallel to the principal axis is refracted and passes
through the principal focus, F.
A ray of light which passes through F is refracted parallel to the
principal axis.

The point of intersection of the rays is a point on the image.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Steps To Take To Draw A Ray Diagram For A Concave Lens

Object F 2F
2F F O

A ray of light passes through the optical centre is undeviated.

A ray of light parallel to the principal axis is refracted and appears to
come from the principal focus, F.
A ray of light travels towards the principal focus, F is refracted parallel
to the principal axis.

The point of intersection of the rays is a point on the image.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Steps To Take To Draw A Ray Diagram For A Concave Lens

Object

Image O F 2F Principal
2F F axis

A ray of light passes through the optical centre is undeviated.

A ray of light parallel to the principal axis is refracted and appears to
come from the principal focus, F.
A ray of light travels towards the principal focus, F is refracted parallel
to the principal axis.

The point of intersection of the rays is a point on the image.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
Further Than 2f , u > 2f

Object

2F F

Characteristics Position of the image Applications
✓ Camera
ITeach – Science Form 4 ✓ Image is formed on
the opposite side of
lens, between F and
2F

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
Further Than 2f , u > 2f

Object Image
F 2F
2F F

Characteristics uv Applications
✓ Camera
✓ real Position of the image
✓ inverted
✓ reduced in size ✓ Image is formed on
the opposite side of
ITeach – Science Form 4 lens, between F and
2F

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
At 2F , u = 2F

Object F F 2F
2F

Characteristics Position of the image Applications

ITeach – Science Form 4 ✓ Image is formed on ✓ Photocopier
the opposite side of ✓ Upright lens
lens, at 2F.

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
At 2F , u = 2F

Object F F 2F Image
2F u v

Characteristics Position of the image Applications

✓ real ✓ Image is formed on ✓ Photocopier
✓ inverted the opposite side of
lens, at 2F.
✓ same size with
object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object Between
F and 2F, F < u < 2F

2F F F 2F

Characteristics Position of the image Applications

ITeach – Science Form 4 ✓ Image is formed on ✓ Projector
the opposite side of ✓ Microscope
lens, beyond 2F.

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object Between
F and 2F, F < u < 2F

Object F F 2F
2F Image

Characteristics uv Applications
Position of the image

✓ real ✓ Image is formed on ✓ Projector
the opposite side of ✓ Microscope
✓ inverted lens, beyond 2F.
✓ Magnified //

Enlarged

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
At F, u = F

FF

Characteristics Position of the image Applications

✓ Image is formed at ✓ Eye lens of
infinity astronomical
telescope

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An Object
At F, u = F

Object F
O
F

Characteristics Position of the image To infinity
No image formed Applications

✓ Image is formed at ✓ Eye lens of
infinity astronomical
telescope

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An
Object Between F And The Lens, u < F

FF

Characteristics Position of the image Applications
✓ Magnifying lens
ITeach – Science Form 4 ✓ Image is formed on
the same side of
lens, as object, but
further away.

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By A Convex Lens For An
Object Between F And The Lens, u < F

Image

Object F
F

u

v

Characteristics Position of the image Applications
✓ Magnifying lens
✓ Virtual ✓ Image is formed on
✓ Upright the same side of
✓ Magnified lens, as object, but
further away.
ITeach – Science Form 4

Characteristics of images formed by a

Position of object convex lens Application

Characteristic of

image

1) Object more than 2F •Real •Camera
•Diminished
•Inverted

2) Object at 2F •Real •Photostat
•Same size machine
•Inverted

3) Object between F and 2F •Real •Microscope
•Enlarged
•Inverted

4) Object at F •Image at infinity •telescope

5) Object less than F •Virtual •Magnifying lens
•Enlarged
•Upright

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image Formed By Concave Lense

The characteristics of the image formed by a concave lens does not
depend on the location of the object.

Object

O F Image

Image formed by a concave lens is always

virtual upright smaller than the
size of the
ITeach – Science Form 4 object //
Diminished

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Image formed by convex lenses

•For a near object, image formed is virtual, upright
and magnified

•For a distant object, image formed is real, inverted
and diminished

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Formation Of Image Plane Mirrors And Lenses

Relationship Between The Thickness Of Convex
Lenses And Its Focal Length
The thicker the convex lens,
the shorter is the focal length

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

7.2 The Formation Of Images By Optical Instrument
Pembentukan Imej Oleh Alatan Optik

ITeach – Science Form 4

Topic 7 Light, Colour A
The Formation Of Image By Optical Instrument

The Formation Of image By Optical Instrument -
Pinhole Camera

Front portion

Pinhole Observer
Translucent screen

Object Image

Black sugar paper

❖ Light enter the box through the pinhole of the camera.

❖ Image formed by pinhole camera is always real and inverted.

ITeach – Science Form 4



Topic 7 Light, Colour A
The Formation Of Image By Optical Instrument

The Characteristics Of The Image Formed By A
Pinhole Camera In Different Conditions

Condition Characteristics of the image

Object is placed closer to the A larger, real and inverted image
pinhole. is formed.

Object is placed further away A smaller, real and inverted image
from the pinhole. is formed.

Smaller pinhole A sharp but dim image is formed.

Bigger pinhole A brighter but blurred image is
formed.
Three pinholes
A convex lens is placed in front Three images are formed.

of the camera. A bright and sharp image is
formed.

ITeach – Science Form 4

Topic 7 Light, Colour A

The Formation Of Image By Optical Instrument -
Periscope

❖ An optical instrument used to view things over an obstacle
such as walls.

❖ Made of a vertical tube with two plane mirrors

❖ Reflection of light occurs 45
Object 45

Plane
mirror

Obstacle Plane
mirror
Image
(upright and 45 Observ
virtual) 45 er
ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Characteristics Of The Image Formed
By A Periscope

Virtual Upright

Same size as the object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Astronomical Telescope Objective lens
(convex)
Eyepiece
lens Light

objective Telescope tube

construction ray
eyepiece

final Information
image
at infinity

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

The Characteristics Of The Image Formed
By A Telescope

Virtual

At infinity

Larger than object

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

The Formation Image By Optical Instrument –
Magnifying Glass

An optical instrument used to observe small
object. (It is actually a convex lens)

Image

Object F
F

u

v

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

The Characteristics Of The Image Formed
By A Magnifying Glass

Larger than the object

Upright

Virtual

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The HuTmheaFnoNrmeartvioonuOsf SIMmyicasrgoteesBcmoypOeptical Instrument -

An optical instrument used to see very tiny objects such as cells and

microorganisms. Ocular Lens

Body Tube (Eyepiece)

Revolving Arm
Nosepiece
Objectives Stage
Stage Clips Coarse
Diaphragm Adjustment Knob
Light Source
Fine
ITeach – Science Form 4 Adjustment Knob

Base

Microscope

Topic 7 Light, Colour And Sight

The Human Nervous System

The Characteristics Of The Image Formed
By A Microscope

Virtual

Inverted

Larger than object

ITeach – Science Form 4

The Human Nervous System
The Human Eyes

Iris Retina
To control the size of pupil To form an image

Pupil
To control the amount
of light which enters

Eye lens
To focus the object

Ciliary muscles
To control the thickness of the lens.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

The Human Eyes

Image formed on ✓ Real
retina is ✓ Inverted
✓ Smaller than the actual size
ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

The Camera

Focus
Diaphragm ring

Camera Film
lens

Aperture

➢ Focusing ring is used to change the position of camera lens
by moving it nearer or further from the film.

Image formed on ✓ Real
camera ✓ Inverted
✓ Smaller than the actual size

ITeach – Science Form 4

Topic 7 Light, Colour A

The Human Nervous System

The Similarities Of The Eye And Camera

Function Eye Camera
Eye lens Camera lens
To focus the object
Pupil Aperture
The opening that allows Retina Film
light rays to enter
Iris Diaphragm
Screen for the formation Ciliary muscles Focus ring
of image

Control the size of the
opening

Change the size lens to
obtain a sharp image

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

Comparing Eye And Camera In Controlling Light
And Focusing In Dark Places

Eye Size of pupil
Camera becomes bigger
to allow
light enter more

Size of aperture is Size of pupil becomes bigger
bigger.

Exposure time is
longer.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

Comparing Eye And Camera In Controlling Light
And Focusing In Bright Places

Eye Size of pupil
Camera becomes smaller
to allow less light
enter.

Size of aperture is Size of pupil becomes smaller
smaller.

Exposure time is
shorter.

ITeach – Science Form 4

Topic 7 Light, Colour And Sight

The Human Nervous System

Comparing Eye And Camera In Focusing A
Distant Object

Ciliary muscles

Eye Eye lens becomes >
Camera thinner.
Light from

distant object

>

Lens becomes
thinner

Camera lens Lens
moves
moves inwards. Light inwards
from
distant >
object >

ITeach – Science Form 4