The document discusses sources of light, categorizing them into natural (like the sun and bioluminescent organisms) and artificial sources (including incandescent and luminescent sources). It also covers the propagation of light, detailing the processes of transmission, reflection, and refraction, along with explanations of different types of reflection and lenses. Finally, it highlights the experiment by Isaac Newton that demonstrated the spectrum of colors in white light.

1. GOOD DAY
GRADE 10

2. SOURCES OF
LIGHTS AND ITS
PROPAGATION

3. 3
When we look at a leaf we know that it is green
because light bounces off the leaf to our eyes to
tell us that it is green.
But what is light?
Which are the sources of light from which
light is originated?

4. 4
Light is electromagnetic radiation. A particular
frequency of this radiation (around 390-700 nm)
is visible to the human eye. Everything that we see
around us is because of light. Light is a form of
energy and like all energies, it is produced from a
source. In Physics, these are called light sources.

5. 5
TYPES OF
LIGHT SOURCES

6. 6
There are countless sources of light, but
they can all be categorized under either
of the two following categories-
•Natural sources
•Artificial sources

7. 7

8. Natural Light
Sources
1

9. 9
The universe is filled with objects that
emit light. Some light from these sources
reaches the earth. The following things in
nature have the ability to emit light:

10. 10
 The Sun is the major source of light for the earth.
The sun is a massive ball of fire, at the center of
which nuclear fusion produces massive energy.
This energy comes out as heat and light. The light
from the sun is one of the major factors behind
the sustainability of life on earth.

11. 11
 Every other star produces light
too, but only a small or no
amount of it reaches the earth
because of the huge distance.

12. 12
 The moon provides light as well but it
cannot produce light on its own. The
light that we get from the moon is the
light reflected by it from the sun.

13. 13
 Some living organisms have the ability to
produce light too. It is called bioluminescence.
It is the effect of certain chemical reactions
within the organism. Fireflies, jellyfish, glow-
worm, certain deep-sea plants, and
microorganisms can be cited as examples.

14. 14
Certain other natural phenomena
such as lightning and volcanic
eruptions also emit light.

15. Artificial
Light Sources
1

16. 16
Apart from natural sources, light can be
produced artificially too. The different
light sources produced artificially can be
put under three broad categories-

17. 17
Incandescent Sources:
When certain objects are heated to a
high temperature, they begin to emit
light. Both infrared and visible light
is produced in the process.

18. 18

19. 19
Luminescent Sources
Light can be produced by accelerating
charges in a luminescent material. One
common way of doing it is bypassing
current through the material.

20. 20

21. 21
Gas Discharge Sources
Passing electricity through
certain gases at very low pressure
can produce light too.

22. 22

23. 23
PROPAGATION
OF
LIGHT

24. 24
refers to the manner in which an
electromagnetic wave transfers its energy
from one point to another. Three main
processes generally occur when light passes
between boundaries from one medium to
another:

25. 25
Three main processes
generally occur when
light passes between
boundaries from one
medium to another:

26. 26
 Transmission of light is the moving of
electromagnetic waves (whether visible light,
radio waves, ultraviolet, etc.) through a
material. This transmission can be reduced, or
stopped when light is reflected off the surface
or absorbed by the molecules in the material.

27. 27
Reflection is when light bounces off an
object. If the surface is smooth and shiny,
like glass, water, or polished metal, the light
will reflect at the same angle as it hit the
surface. This is called specular reflection.

28. 28
TYPES
OF
REFLECTION

29. 29
1. specular reflection.
Light reflects from a smooth surface at the
same angle as it hits the surface. For a smooth
surface, reflected light rays travel in the same
direction.

30. 30
The angle at which light hits a reflecting surface
is called the angle of incidence, and the angle
at which light bounces off a reflecting surface is
called the angle of reflection.

31. 31
Water is also a reflective surface. When
the water in a lake or sea is very still, the
reflection of the landscape is perfect,
because the reflecting surface is very flat.
However, if there are ripples or waves in
the water, the reflection becomes
distorted. This is because the reflecting
surface is no longer flat and may have
humps and troughs caused by the wind.

32. 32
2. Diffuse reflection
For a rough surface, reflected light rays
scatter in all directions.

33. 33
is when light hits an object and reflects in
lots of different directions. This happens
when the surface is rough. Most of the things
we see are because light from a source has
reflected off it.

34. 34
For example, if you look at a bird, light has
reflected off that bird and traveled in nearly all
directions. If some of that light enters your eyes, it
hits the retina at the back of your eyes. An
electrical signal is passed to your brain, and your
brain interprets the signals as an image.

35. 35
is the bending of light (it also happens with
sound, water, and other waves) as it passes
from one transparent substance into
another.
REFRACTION

36. 36
This bending by refraction makes it possible for us
to have lenses, magnifying glasses, prisms, and
rainbows. Even our eyes depend upon this bending
of light. Without refraction, we wouldn’t be able to
focus light onto our retina.

37. 37
Lenses
A lens is simply a curved block of glass
or plastic. There are two kinds of lenses.

38. 38
Converging lens
A biconvex lens is thicker in the middle than it
is at the edges. This is the kind of lens used for a
magnifying glass. Parallel rays of light can be
focused on a focal point. A biconvex lens is
called a converging lens.

39. 39
Converging lens
Each light ray entering a converging (convex) lens
refracts inwards as it enters the lens and inwards
again as it leaves. These refractions cause parallel
light rays to spread out, traveling directly away
from an imaginary focal point.

40. 40
Converging lens

41. 41
Concave lens
Each light ray entering a diverging (concave) lens
refracts outwards as it enters the lens and outwards
again as it leaves. These refractions cause parallel
light rays to spread out, traveling directly away from
an imaginary focal point.

42. 42
A biconcave lens curve is thinner in the middle
than it is at the edges. Light rays refract outwards
(spread apart) as they enter the lens and again as they
leave.
Concave lens

43. 43
Converging lens

44. 44
Refraction can create a spectrum
Isaac Newton performed a famous experiment using
a triangular block of glass called a prism. He used
sunlight shining in through his window to create a
spectrum of colors on the opposite side of his room.

45. 45
This experiment showed that white
light is actually made of all the
colors of the rainbow. These seven
colors are remembered by the
acronym ROY G BIV – red, orange,
yellow, green, blue, indigo and
violet.

46. THANK YOU
FOR
LISTENING

47. 47

48. 48

49. 49

50. In two or three columns
Yellow
Is the color of gold,
butter and ripe
lemons. In the
spectrum of visible
light, yellow is
found between
green and orange.
Blue
Is the colour of the
clear sky and the
deep sea. It is
located between
violet and green on
the optical
spectrum.
Red
Is the color of
blood, and because
of this it has
historically been
associated with
sacrifice, danger
and courage.
50

51. Want big impact?
Use big image.
51

52. Use diagrams to explain your ideas
52
Lorem Ipsum
Lorem Ipsum Lorem Ipsum
Lorem Ipsum
Lorem Ipsum
Lorem Ipsum
Lorem Ipsum

53. And tables to compare data
A B C
Yellow 10 20 7
Blue 30 15 10
Orange 5 24 16
53

54. Maps
our office
54
Find more maps at slidescarnival.com/extra-free-resources-icons-and-maps

55. 89,526,124$
That’s a lot of money
100%
Total success!
185,244 users
And a lot of users
55

56. Our process is easy
56
Lorem 3
Lorem ipsum dolor sit
amet, consectetur
adipiscing elit. Duis sit
amet odio vel purus
bibendum luctus. Morbi
iaculis dapibus tristique.
In hac habitasse platea
dictumst.
Lorem 1
Lorem ipsum dolor sit
amet, consectetur
adipiscing elit. Duis sit
amet odio vel purus
bibendum luctus. Morbi
iaculis dapibus tristique.
In hac habitasse platea
dictumst.
Lorem 2
Lorem ipsum dolor sit
amet, consectetur
adipiscing elit. Duis sit
amet odio vel purus
bibendum luctus. Morbi
iaculis dapibus tristique.
In hac habitasse platea
dictumst.

57. Let’s review some concepts
Yellow
Is the color of gold, butter
and ripe lemons. In the
spectrum of visible light,
yellow is found between
green and orange.
Blue
Is the colour of the clear sky
and the deep sea. It is
located between violet and
green on the optical
spectrum.
Red
Is the color of blood, and
because of this it has
historically been associated
with sacrifice, danger and
courage.
57
Yellow
Is the color of gold, butter
and ripe lemons. In the
spectrum of visible light,
yellow is found between
green and orange.
Blue
Is the colour of the clear sky
and the deep sea. It is
located between violet and
green on the optical
spectrum.
Red
Is the color of blood, and
because of this it has
historically been associated
with sacrifice, danger and
courage.

58. You can insert graphs from Excel or Google Sheets
58

59. Mobile project
Show and explain your
web, app or software
projects using these
gadget templates.
59

60. 60
Tablet project
Show and explain your
web, app or software
projects using these
gadget templates.

61. 61
Desktop project
Show and explain your
web, app or software
projects using these
gadget templates.

62. Thanks!
Any questions?
You can find me at:
✗ @username
✗ user@mail.me
62

63. Credits
Special thanks to all the people who made and
released these awesome resources for free:
✗ Presentation template by SlidesCarnival
✗ Photographs by Unsplash
63

64. Presentation design
This presentation uses the following typographies:
✗ Titles: Amatic SC
✗ Body copy: Nunito
Download for free at:
https://www.fontsquirrel.com/fonts/amatic
https://www.fontsquirrel.com/fonts/nunito
You don’t need to keep this slide in your presentation. It’s only here to serve you as a
design guide if you need to create new slides or download the fonts to edit the
presentation in PowerPoint®
64

65. Extra resources
65

66. 66
Find more icons at slidescarnival.com/extra-free-
resources-icons-and-maps
SlidesCarnival icons are editable shapes.
This means that you can:
✗ Resize them without losing quality.
✗ Change fill color and opacity.
✗ Change line color, width and style.
Isn’t that nice? :)
Examples:

67. Diagrams and infographics
67

68. ✋👆👉👍👤👦👧👨👩👪💃🏃💑❤😂😉
😋😒😭👶😸🐟🍒🍔💣📌📖🔨🎃🎈🎨🏈
🏰🌏🔌🔑 and many more...
😉
68
You can also use any emoji as an icon!
And of course it resizes without losing quality.
How? Follow Google instructions
https://twitter.com/googledocs/status/730087240156643328

69. Free templates for all your presentation needs
Ready to use,
professional and
customizable
100% free for personal
or commercial use
Blow your audience
away with attractive
visuals
For PowerPoint and
Google Slides