3. 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.
4. Light travels VERY FAST – about
300,000 kilometers per second or
186,000
186 000 miles per second
second.
At this speed light
could travel the
equivalent of 8 times
q f
around the world in
one second!
5. Light can create shadows
Shadows are places where light is “blocked”:
Rays of light
6. Light travels in waves
A wave is a disturbance that transfers
energy from place to place.
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7. What characteristics do light
waves h
have? ?
Light waves are like other kinds of waves.
They have crests, troughs, wavelength,
frequency and speed. However, light waves
are electromagnetic! Light waves have a
component that is electric and magnetic!!
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8. We see things because they
g y
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
H k
9. Light is a form of energy called
Electromagnetic Radiation -
Electromagnetic Radiation comes f
El i R di i from the sun and
h d
other sources
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10. Electromagnetic Radiation
•Travels at the speed of
light
•Is mostly i i ibl
I tl invisible
•Carries energy
•Is VERY important to
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society and is something
are needed to see this picture.
YOU can’t be without for
many reasons
11. Types of electromagnetic
radiation
Radio and TV - Great for broadcasting
Microwave-Super for cell phones, microwaves
Infrared-Think HEAT
Visible Light - Yep, it’s how we see
Ultraviolet Invisible, can cause c ncer;
Ultr vi let - Invisible c n c use cancer; kills germs
erms
Xray- images of bones and teeth; space exploration
Gamma - treating cancer (radiation therapy)
12. Properties of Light summary
1) Light travels in straight lines and is a form of
energy
2) Light travels much faster (a million times faster!)
than sound
3) We see things because they reflect light into our
eyes
e es
4) Shadows are formed when light is blocked by an
object
5) Visible light is only a small part of the
electromagnetic spectrum; the other parts are
invisible to the human eye but not necessarily the
um y u y
eyes of other animals.
14. Regular vs. Diffuse Reflection
Smooth, shiny surfaces
m , y u f
have a regular
reflection:
Rough, dull surfaces have
h d ll f h
a diffuse reflection.
Diffuse reflection is when
light is scatt r in
ght s scattered n
different directions
16. Types of Mirrors: Plane, Concave, Convex
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Plane mirrors are flat and make “virtual
images”. Th images is “virtual” because the
im s” The im s i t l” b s th
light rays do not come from the image, they
only appear to
17. Concave Mirrors are curved inward - just
remember, you go “i ” t a cave, and “in” to a
b “in” to d “i ” t
concave mirror!
Virtual
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The “mirage” box on Mr. S’s desk is
g
made of two concave mirrors.
Images of concave mirrors can be
virtual or real!
i t l l!
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18. Convex mirrors are mirrors that curve outward
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Convex mirrors are used for
security purposes, in cars etc.
They ll
Th allow us to see a wide
st s id
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view. The images they make
are virtual
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19. 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
m g y p g g p
5. Real images - always upside down and are
formed when light rays actually meet
20. Refraction
•Refraction is when waves speed up or slow down due to
travelling in a different medium
g
•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
21. The degree that light bends when it enters a
g g
new medium is called the “index of refraction”
23. Lenses work because of refraction! Light is
bent as it enters a new medium glass!
medium,
Convex lenses
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1.
1 Thicker middle,
Thick r in middl thin on edges
n d s
2. Light rays meet to form a focal point
3.
3 Makes real images since light rays come together from
a light source, but can also make virtual images (center
picture)
4. Used i
4 U d in cameras, t l
telescopes, human eye
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24. Concave Lenses
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1. Concave lenses are thin in the middle and
thicker on the edges
2. Since light rays never meet with this lens,
they make virtual images only
3. Used in cameras & telescopes to correct
spherical aberation, and also eyeglasses
25. Review of Refraction
1. Light rays slow down when they enter a new
medium
di
2. Refraction can cause light rays to change
their direction
3. All transparent materials have their own
p
“index of refraction”
4.
4 Light is refracted when it passes through
lenses and this creates images
26. 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
us.
27. Yes, we LOVE color!
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28. Color
White light is not a single color; it is made up of a
mixture of the seven colors of the rainbow.
We can demonstrate this by
splitting white light with a
prism:
This is how rainbows are
formed: sunlight is “split up”
g p p
by raindrops.
29. The colors of the rainbow:
Red
Orange
Yellow
Green
Blue
Indigo
Just remember ROY G. BIV Violet
30. Adding colors of light
White light can be split up to make separate colors.
These colors can be added together again.
The primary colors of light are red, blue and green:
Adding blue and red Adding blue and
m
makes magenta
m g green makes cyan
g m y
(purple) (light blue)
Adding red Adding all
and green
g three makes
makes yellow white again
31. Seeing color
The color an object appears depends on the colors of
light it reflects.
For example, a red book only reflects red light:
p y g
White Only red light
light is reflected
fl d
32. In different colors of light this shirt would look different:
Red
Shirt looks red
light
Shorts look black
Shirt looks black
Blue
light
Shorts look blue
33. 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 colors:
White
light
34. Using filters
Filters can be used to “block” out different colours of light:
Red
R d
Filter
Magenta
Filter
Fl
35. Some further examples:
Color object
Object Color of light
seems to be
Red Red
Red socks Blue Black
Green Black
Red Black
Blue teddy Blue
Green
Red
Green camel Blue
Green
Red
Magenta book Blue
Green
38. Part 2 - Reflection and
Mirrors
Mi
Reflection from a mirror:
Normal
Incident ray
y Reflected ray
y
Angle of Angle of
incidence reflection
Mirror
39. The Law of Reflection
Angle of incidence = Angle of reflection
In other words, light gets reflected from a surface at
g g
____ _____ angle it hits it.
The
Th
same !!!
40. Brain Pop Movie on Color
p
Brain Pop Movie on Color! Enjoy it!
p j y
View the movie on Color from Brain Pop. Then take the
p
quiz at the end of the movie. How did you do?
