The document discusses various properties of visible light, including that it is part of the electromagnetic spectrum detectable by the human eye, with wavelengths between 380-740 nanometers. It describes how light interacts with different materials by being transmitted, reflected, or absorbed, and can be refracted or reflected, with refraction causing changes in speed and direction as light passes into new mediums. The concepts of albedo, reflection, refraction, index of refraction, and angles of incidence and refraction are also introduced.

1. Properties of Visible Light

2. Light waves
• All waves in the
electromagnetic spectrum are
light waves
• Visible light – part of the
spectrum that humans CAN
see
• Human eyes are equipped
with special cone-shaped cells
that act as receivers to the
wavelengths of visible light.
• Human eyes detect the
brightness, or intensity, of
visible light, which is
determined by the amplitude
of a light wave
• The range of wavelengths of
visible light is from about 380
nanometers to about 740
nanometers; human eyes do
not detect wavelengths
outside of this range
• The visible light range further
divides into smaller regions
depending on wavelength;
humans recognize these
smaller regions as colors.

4. “Color” Discovery Education
Streaming Movie (Look at the
video at the right)
1. What happens to visible light as it passes through a
prism that produce colored light?
• Visible light refracts, or bends., as it enters and leaves
a prism. The different colors refract by lightly
different amounts, so they separate.
2. What is the order of the colors of refracted light?
• Red, orange, yellow, green, blue, indigo, and violet.
3. How do rainbows form?
• Rainbows form when sunlight passes through
raindrops, which act as prisms, that separate the light
into colors
4. Why does a yellow flower appear yellow?
• A yellow flower appears yellow because it absorbs all
the colors of visible light, except yellow, which it
reflects
5. Why does a black notebook appear black?
• A black notebook appears black because it absorbs
ALL the colors of visible light and does NOT reflect any
color.
Watch the video ^^

5. Transparent, Translucent, and Opaque
• Light waves travel in strait
lines from their source.
• When a light wave strikes an
object, the light will do three
things: transmit (go through
an object), reflect (to bounce
off an object), and/or absorb
(the energy of the light wave
transforms into heat).
• Certain descriptions of matter
are based on the way light
interacts with it.
Transparent objects:
• Lets nearly all the light that strikes them to pass
through.
• Example: a piece of glass
• Are see-through
Translucent objects:
• Scatters the light that passes through them
• Example: a frosted window
• Are partially see-through
• You can usually see something behind a translucent
object, but not the details
Opaque objects:
• Either reflect or absorb all the light that strikes
them
• Example: brick wall
• Are NOT see-through because light cannot pass
through them
• The color of an opaque object comes from the
color it reflects (look back at slide 4)

6. Translucent panes of glass
Opaque object (brick
wall)
Transparent object (see-
through glass)

7. Watch the video ^^ and answer the
questions below.
1. Match the type of material with its proper description:
Wax paper a. transparent
Aluminum foil b. translucent
Clear plastic c. opaque
2. How did persistence of vision allow you to see the image reflected
from the dowel rod?
***Answers are on next slide. 

8. Answer to number 1:
- Wax paper – translucent
- Aluminum foil – opaque
- Clear plastic – transparent
Answer to number 2
- Persistence of vision is a phenomenon whereby your eyes retain an image for
a fraction of a second. This enabled you to see a whole image even though the
reflected light came to you in pieces on the dowel rod.
Answers to slide 7

9. Albedo
• Different materials reflect
different amounts of light
from their surfaces. Albedo
is the percentage of light
reflected off a surface. The
chart to the right shows the
albedo, or reflectivity, of
various surfaces.
Albedo of Various Surfaces
Fresh snow 80-95%
Thick clouds 60-90%
Thin clouds 30-50%
Sand 15-45%
Ice 30-40%
Earth and
atmosphere
30%
Grass 10-30%
Dry soil 5-20%
Wet soil 10%
Water 10% (daily average)

10. Look at the video at the
right.
What is the albedo of moon dust?
- The albedo of moon dust is between 7-
10%.
Look at the chart on the previous slide.
Which substances have about the same
reflectivity as moon dust?
- Water, wet soil, and grass have about the
same reflectivity as moon dust.
How did simulating the albedo of the
moon’s surface help the scientists in the
movie?
- The scientists were able to prove that a
photograph of the lunar landing was not a
fake because the albedo of the moon’s
surface provided sufficient lighting from
reflected sunlight to make the photograph
possible.
“Replicating the Moon’s Reflective Surface
Discovery Education Video

11. Other Properties of Light
• Remember, when light waves
encounter a medium (or object) they
can be transmitted, reflected, or
absorbed.
• When light rays are transmitted, they
will refract in the new medium. (To
make it easier, when light waves go
through an object, the light wave
changes speed and/or direction).
**Make sure you remember the
difference between wave refraction and
reflection. Also remember what a
medium is. Reflection happens when a
wave bounces off a medium without
entering it. Refraction occurs when a
wave changes speed and/or direction
upon entering a new medium .
• When light waves encounter a
medium, they can reflect from the
medium in two ways. Look below:
Regular reflection
 Occurs when parallel rays of light
bounce off a smooth medium or
surface at the same angle, producing
an image on the surface of the
medium
 Is also called specular reflection
Diffuse reflection
 Occurs when parallel rays of light
bounce off of a bumpy or uneven
medium or surface at different
angles, producing either an unclear
image or no image at all.

13. Lets take a closer look at reflection of light
waves
True or False: The reason you are able to see
anything is because light reflects off objects.
• True
What happens to light waves when they reflect off
a rough surface?
• The light scatters in different directions.
What happens to light waves when they reflect off
a smooth surface?
• The light bounces off in one direction.
What results when light waves bounce off a
smooth surface in one direction?
• An image of the object reflects from the
surface.
What makes something appear dull instead of
shiny?
• If the surface of an object is not smooth, light
reflecting from the surface will scatter in
different directions, and the object will appear
dull instead of shiny.
Watch the “Light Reflection:
Dependent on Surface” Video

14. Now take a closer look at refraction of light
waves
Why does the pencil in the video
appear to bend in water?
• Light waves bouncing off the lower
end of the pencil bend as they
travel from the water to the air.
This makes the pencil appear bent.
Why does the seashell in the video
appear to be in a location in which it
really was not?
• Light waves bouncing off the
seashell bend as they travel from
the water to the air. This makes the
seashell appear to be in a different
location.
Look at the “Refraction: The
Bending of Light Waves” video

15. Index of refraction, angle of incidence, and angle
of refraction
index of refraction of a medium:
 Measures how many times
SLOWER a light wave will travel in
a medium versus in a vacuum.
 Example: the index of refraction
of water is 1.33 at 20 degrees
Celsius. This means that a light
wave will travel 1.33 times slower
in water than in a vacuum
 The larger the index of refraction,
the slower the wave travels in a
medium
Angle of incidence
 The angle at which a light waves
enters a medium
Angle of refraction
 The angle at which a light wave
refracts, or bends, as it travels
through the new medium

16. Both the angle of incidence and the angle of
refraction are measured between the light ray
and the dotted line called the normal.