Light
Thomas Edison

In 1879, Thomas Edison
finally succeeded find light
bulb after failed in thousand
experiments
Where does light come from?
Our major
light source:
the Sun
Where else does light come from?
Luminous and non luminous object

https://www.youtube.com/watch?v=UV4C9PH8qws
Sorting light sources
Natural
vs.
Man-made (artificial)
Are these light sources?
moon
mirror
water
These items are not light sources, instead they
are reflecting light from other sources.
The Uses of lights

To help us see

To finds things easily

To help plants growing
Can you think an object that some
people might mistake for a light
source, but is not?
Telescope

Early telescopes focused
light using pieces of
curved, clear glass, called
lenses. However, most
telescopes today use
curved mirrors to gather
light from the night sky.
The shape of the mirror
or lens in a telescope
concentrates light. That
light is what we see when
we look into a telescope.
microscope

The light microscope is an
important tool in the study
of microorganisms,
particularly for
identification purposes. The
compound light microscope
uses visible light to directly
illuminate specimens in a
two-lens system, resulting in
the illuminated specimen
appearing dark against a
bright background
camera

a camera is an optical
instrument used to record
images.At their most
basic, cameras are
sealed boxes
(the camera body) with a
small hole (the aperture)
that allow light in to
capture an image on
a light-sensitive surface
(usually photographic film
or a digital sensor)
Solar panel

The solar cells that you
see on calculators and
satellites are also called
photovoltaic (PV) cells,
which as the name
implies (photo meaning
"light" and voltaic
meaning "electricity"),
convert sunlight directly
into electricity.
Other natural sources
Light intensity

Which appears brighter? Why?
Light intensity

Which appears brighter? Why?
The temperature of the star
determine its color. The hottest,
the brighter will be
Sort the sources of light from the
brightest to the dimmest
Light Intensity

Light intensity : the quantity of visible light that is emitted

Light intensity can be measured using lux meter or
photometer, the unit is light
Light intensity with various
distances

find the differences from the
picture

find the differences from the
picture :

Light spreads out over a
wider are. The furthest, the
widest will be.

The further light sources, he
dimmer will be
MEASURING LIGHT INTENSITY
GUIDED QUESTION

Does the distance between
lux/photo meter and light sources
matter?

Which one is brighter, indoor with
many led lamps, or outdoor with
sun light?
Time to experiment

Your teacher will be doing the demonstration to answer your
guided questions
Table of light intensity (Lux)
Indoor with
lamps
Outdoor with
lamps
Nearest distance
Closest distance
Experiment report

Claims

Evidences

Explanation
It’s time to do experiment at home

Please kindly install lux meter/photometer on your device

You will be doing experiment to measure light intensity in
science class tomorrow :
Prepare for tomorrow:
1.
Lux / photo meter
2.
Night light
3.
Table lamp
4.
Torch
5.
Sun light
6.
A piece of paper
Light Intensity

The further the light source is, the dimmer the light seems. That
happens because the light spreads out over in wider area

The brighter the light source is, the darker the shadow it cast. It
happens because the more intensity of the light, the more ambient will
be cut-off
Guided Question

Which one is the brightest
between night light, table lamp,
torch, and day light?

Which shadow is brighter, the
shadow from the table lamp or
the shadow from the torch?
Experiment report
Table of experiment
Object
Light intensity (Lux)
Night light
25
Table lamp
290
Torch
677
Day light
14530
Which shadow is darker

Now measure the light intensity of shadows from lamp and
sun light

This time, put the lux meter 10 cm away from table lamp
and torch.

After that put paper between lux meter and light sources

Write down the result of light intensity of shadows
Shadow of table lamp
Shadow of torch
39
42
Experiment report

Claims

Evidences

Explanation
Review

QUIZZIZ

https://quizizz.com/admin/quiz/5e631e54741932001c4888
04/sources-of-light
How Light
Travels
Observe from these pictures, between the
center and the edge of light, Which part of
the light is brighter?

Light is brighter in the center
Light Patch

The patch of the light made by
the torch grows larger and
dimmer
How light travels

Based on this virtual experiment, find out :
https://www.sciencekids.co.nz/gamesactivities/howwesee.html
a.
What line does the light travel?
Straight line
a.
What happen to the light once it hit the mirror?
It’s reflected and the direction changes
Ray Diagram

All rays of light are travelling in different direction, in straight
line and outwards from the source

A light sources gives out many/an uncountable
number/millions/an infinite number of rays

You could draw more or fewer rays, longer or shorter but you
COULD NOT CHANGE the direction and the straight line
Draw the rays of light of
following light source
Draw the ray diagram of light
of following light source
Draw the rays of light of
following light source
Draw the rays of light of
following light source
Draw the ray diagram of light
of following light source
LIGHT
REFLECTION
What things can reflect the light?
Have you ever gone to the
dentist?

What is the function of this tool?
Light Reflection in Rays
Watch the following video, and infer, what thing can reflect the
light?
https://www.youtube.com/watch?v=ETF2-Zz3J18
Can light be reflected many
times?

https://www.cokogames.com/light-reflection-game/play/
We put a lot of mirror. The more mirror be put, the more light would
be reflected many times
Reflection of Ray diagram

Rays will be reflected once it hits the mirror.

Rays/light travels In straight line
Draw the ray diagram based on
picture below

Nonluminous
object
needs
light in
order to
be seen

Luminou
s object
is
directly
reflecte
d to our
eyes
Incident ray

Now draw the reflection diagram
of these following thing
Now draw the reflection diagram
of these following things
Reflection of us in a mirror
What object could reflect the
light?
Identify 3
similarities
between them:
1. They have
smooth
surfaces
2. They are
shining
3. They reflect
the object
in front of
them
Characteristic of good light
reflector

It has smooth surface

It is shiny

It reflects object in front of it

the shinier things, it reflects better, and the clearer
reflection image, the better things reflect light
COMPARE TWO OBJECTS BELOW,
WHICH ONE IS BETTER
REFLECTOR

the shinier things, it reflects better, and the clearer
reflection image, the better things reflect light
COMPARE TWO OBJECTS BELOW,
WHICH ONE IS BETTER
REFLECTOR

the shinier things, it reflects better, and the clearer
reflection image, the better things reflect light
Find things around you

FIND 5 THINGS AROUND YOU THAT CAN REFLECT THE
LIGHT in 7 MINUTES, AND LIST THEM ON YOUR SCIENCE
NOTE BOOK

SHARE YOUR FINDINGS WITH YOUR FRIENDS
Materials for tomorrow

Materials:
1.
Mirror
2.
Glass window
3.
Plastic spoon/Metal spoon
4.
Ceramic tile/ wooden floor
5.
Piece of paper

Printed worksheet or science notebook to write down
the answer

Ruler and stationery
THE
CHARACTERISTIC
OF GOOD
REFLECTOR
What make things could be good light reflector?
Which surfaces reflect light
best?
Drawing the bar chart
Identify the surface area
characteristics of the best light
reflector
SUBMIT THE WORK TO
GOOGLE CLASSROOM
Sort these objects from left to
right, from the worst to the best
light reflector
The advantage of light
reflection

Mirrorred letter on Ambulance

Why AMBULANCE is written as ECNALUBMA on
emergency vehicles?
Mirror writing is formed by writing in the direction
that is the reverse of the natural way for a given
language, such that the result is the mirror image
of normal writing: it appears normal when it is
reflected in a mirror
So that ambulance car could get through the
crowded highway easily because people easily
read the ambulance letter from their car wing
mirror
LAW OF REFLECTION

The law of reflection states that
•
The incident ray, the reflected ray and the normal all lie in the same plane
•
The angle of incidence = Angle of reflection
Draw the incident ray,
reflected ray, incidence angle,
reflected angle, and normal
line
PREPARE TOMORROW’S
MATERIAL

Materials:
1.
Laser (it’s a must)
2.
White paper A4
3.
Pencil
4.
Protractor
5.
Ruler
Printed worksheet or note book to write the answer
Types of Reflection of Light
Regular reflection

Give 5 example of regular reflection
Diffused reflection

Give 5 example of regular reflection
Review

https://quizizz.com/admin/quiz/5d3bd0518e7b16001f6
cf184/reflection
HOW WE SEE
THINGS
How the eyes work?

https://www.generationgenius.com/videolessons/lightreflection-and-vision-video-for-kids/
HOW WE SEE THINGS

LIGHT TRAVELS IN STRAIGHT LINE

LIGHT TRAVELS IN WHITE LINE

WHEN LIGHT TRAVELS TO OUR EYES, THE IMAGES ARE TURNED UPSIDE DOWN

ONLY THE OBJECT COLOR WILL BE REFLECTED TO OUR EYES, AND THE REST
COLOR WILL BE ABSORBED
ONLY THE OBJECT COLOR WILL BE REFLECTED TO OUR EYES,
AND THE REST COLOR WILL BE ABSORBED
EYES EXERCISE

Bring a pencil and put it away 5 cm from eyes

Close one of your eyes

Bring the pencil closer and away 3 times

What did you see? Did you see it blurry?
BLURRY VISION

DEFOCUS : In optics, defocus is the aberration in which an image is
simply out of focus.

In general, defocus reduces the sharpness and contrast of the image.
What should be sharp, high-contrast edges in a scene become gradual
transitions. Fine detail in the scene is blurred or even becomes
invisible. Nearly all image-forming optical devices incorporate some
form of focus adjustment to minimize defocus and maximize image
quality.
EYES FOCUS TEST

Prepare your paper and pencil to take a note

DISCLAIMER : This test is not accurate, the accurate one
should be conducted by doctors

https://www.youtube.com/watch?v=YAxLueEKqmU
EYES

Watch this video and refer the conclusion

https://www.youtube.com/watch?v=axpCN6Vj9p0

What are the part of eyes?
What makes your vision
blurry after doing eyes
exercise?
HOW THE EYES WORK?

Our brain help us to turn the upside
down images to normal
LABELLING EYES

https://online.seterra.com/en-an/vgp/3802
REVIEW

https://quizizz.com/join/game/U2FsdGVkX18tYcx%252
FnOqt3M0eguO3VdE3w3HtPUNwRC1xhImyEF0LlafWo5g3F
8CmXpbeG9Jn1ludU%252FlDCFP9zg%253D%253D?gameTy
pe=solo
EYES DISFUNCTIONS
Presbyopia/Myopia

Farsightedness:
can’t see close up

Nearsightedness:
can’t see far away
Colorblindness

X linked recessive trait that
causes a problem with the
color-sensing granules
(pigments) in cones.

most severe form of color
blindness is achromatopsia

rare condition in which a
person can’t see any color, so
they see everything in shades
of gray.
If just one pigment is missing,
you may have trouble telling
the difference between red and
green. This is the most common
 lazy eye, nystagmus (small,
type of color blindness.
jerky eye movements),
 If a different pigment is
severe light sensitivity, and
missing, you may have trouble
extremely poor vision.
seeing blue-yellow colors.

People with blue-yellow color
blindness usually have problems
Astigmatism

optical defect in which
vision is blurred due to
the inability of the
optics of the eye to
focus a point object into
a sharp focused image
on the retina.

due to an irregular or
toric curvature of the
cornea or lens.
Glaucoma
Increased amount of pressure in the eye
damage to the optic nerve is due to
increased pressure in the eye, also known
as intraocular pressure (IOP).
Cataracts
A cataract is a clouding of the lens in the eye that
affects vision. Most cataracts are related to aging.
By age 80, more than half of all Americans either
have a cataract or have had cataract surgery.
Retinal detachment
Conjunctivitis
Diplopia
Cornea
transplant
lasik