It is a very interesting ppt about the properties of light ,mirrors ,refraction ,colors etc.

1. By Khan Imran

3. What Is Light?
In this PowerPoint presentation:
1)
2)
3)
4)
Properties of light
Colours
Reflection - Mirrors
Refraction - Lenses

4. Properties of Light
Light travels in straight lines:
Laser

6. 2.Light travels much faster than sound. For
example:
1) Thunder and lightning
start at the same
time, but we will see
the lightning first.
2) When a starting pistol
is fired we see the
smoke first and then
hear the bang.

8. 3.Light travels VERY FAST – about
300,000 kilometres per second or 186,000
miles per second.
At this speed light
could travel the
equivalent of 8 times
around the world in
one second!

10. 4.Light can create shadows
Shadows are places where light is “blocked”:
Rays of light

12. We see things because they reflect
light into our eyes! This is literally
the only way we get to see things!
ALL objects we see either create light
or reflect light!!
Homework

13. Light is a form of energy called
Electromagnetic Radiation.
Electromagnetic Radiation
and other sources
comes from the sun

14. Properties of Light summary
1) Light travels in straight lines and is a form of
2)
3)
4)
5)
energy
Light travels much faster (a million times faster!)
than sound
We see things because they reflect light into our
eyes
Shadows are formed when light is blocked by an
object
Visible light is only a small part of the
electromagnetic spectrum; the other parts are
invisible to the human eye but not necessarily the
eyes of other animals.

15. Part 2 - Reflection and Mirrors

16. Regular vs. Diffuse Reflection
Smooth, shiny surfaces
have a regular
reflection:
Rough, dull surfaces
have a diffuse
reflection.
Diffuse reflection is
when light is scattered
in different directions

18. Review of Reflection
1. Two types of reflection, regular and diffuse
2. Mirrors come in 3 types: plane, convex and
concave. Each has a distinct shape and use.
3. Mirrors can make virtual images or real
images depending on their type
4. Virtual images - light rays do not meet and
the image is always upright or right-side-up
5. Real images - always upside down and are
formed when light rays actually meet

19. Using mirrors
Two examples:
2) A car headlight
1) A periscope

20. Types of Mirrors: Plane, Concave, Convex
Plane mirrors are flat and make “virtual
images”. The images is “virtual” because the
light rays do not come from the image, they
only appear to

22. Concave Mirrors are curved inward - just
remember, you go “in” to a cave, and “in”
to a concave mirror!

24. Convex mirrors are mirrors that curve outward
Convex mirrors are used for
security purposes, in cars
etc. They allow us to see a
wide view. The images they
make are virtual

26. Refraction
•Refraction is when waves speed up or slow
down due to travelling in a different
medium
•A medium is something that light waves
will travel through
•Light rays are slowed down by the water
•Causes the ruler to look bent at the
surface
• The mediums in this example are water
and air .

27. The degree that light bends when it enters a
new medium is called the “index of refraction”

28. Light hitting at an
angle is bent
Light hitting
straight on is
not bent

29. Review of Refraction
1. Light rays slow down when they enter a
new medium
2. Refraction can cause light rays to change
their direction
3. All transparent materials have their own
“index of refraction”
4. Light is refracted when it passes through
lenses and this creates images

31. Color
Part 3 - Color In this section of the PowerPoint
you will learn about color and how we can mix
colors to create other colors. We will also
learn how light helps us to see various colors
around us.

32. Colour
White light is not a single colour; it is made up of
a mixture of the seven colours of the rainbow.
We can demonstrate this
by splitting white light
with a prism:
This is how rainbows are
formed: sunlight is “split
up” by raindrops.

33. The colours of the rainbow:
Red
Orange
Yellow
Green
Blue
Indigo
Violet
Just remember ROY G. BIV

35. Adding colours of light
White light can be split up to make separate
colours. These colours can be added together
again.
The primary colours of light are red, blue and
green:
Adding blue and
red makes magenta
(purple)
Adding red
and green
makes yellow
Adding blue and
green makes cyan
(light blue)
Adding all
three makes
white again

36. Seeing colour
The colour an object appears depends on the
colours of light it reflects.
For example, a red book only reflects red light:
White
light
Only red light
is reflected

37. A pair of purple trousers would reflect purple light
(and red and blue, as purple is made up of red and
blue):
Purple light
A white hat would reflect all seven colours:
White
light