# Light and Color - PowerPoint

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```					     Light and Color

EQ: How does light interact with
matter?
Light and Matter
• Three ways light interacts with matter
– Reflection
– Absorption
– Transmission
• Example – Window
– You can see objects outside because light is
transmited through the glass

EQ: How does light interact with matter?
Transmission
• Passing of
light through
matter
• Transmission
of light occurs
all the time,
through air

EQ: How does light interact with matter?
• Example – Window
– You can see objects outside because light is
transmitted through the glass
– You can see the glass and your reflection in it
because light is reflected off the glass
– The glass feels warm when you touch it
because some light is absorbed by the glass

EQ: How does light interact with matter?
Vocabulary
Transparent – a
material that
transmits light.
Light passes
through it
allowing you to
see what is on
the other side
EQ: How does light
interact with matter?
Translucent
A material that
scatters light as it
passes through it.
Only some light
passes through
the material
EQ: How does light
interact with matter?
Opaque
A material that
reflects or
absorbs all of the
light that strikes
it. You cannot
see through it
EQ: How does
light interact with
matter?
How do we see color?
• We see different
wavelengths of light as
different colors
– Long wavelengths as red
– Short wavelengths as
violet
– Certain combinations of
color like pink and brown
are seen when certain
combinations of
wavelengths are present      EQ: How does light
interact with matter?
Color of an Object
The color that an object appears to be is
determined by the wavelengths that reach

Light reaches your eye after being reflected or
after being transmitted through an object

Your brain interprets the color

EQ: How does light
interact with matter?
Colors of Opaque Objects
• When white light strikes an opaque object,
some colors are absorbed and some are
reflected.
• Only the reflected light reaches your eyes and
is detected
• The color of light reflected by an opaque object
determine the color you see.
EQ: How
does light
interact with
matter?
Colors of Transparent and
Translucent Object
• When you look through
colored transparent or
translucent objects, you see
the color of light that was
transmitted through the object.
The other colors were
absorbed
EQ: How does light
interact with matter?
Mixing Colors of Light
• Primary colors of light
red, blue, green
when these three colors of light are
mixed the light appears white

EQ: How does
light interact
with matter?
• Combining colors of
light
• Secondary color of
light
– When two primary
colors of light are
combined
• Cyan = blue + green
• Magenta = blue + red
• Yellow = red + green
EQ: How does light
interact with matter?
Light and Color Television
• Color tv is produced by color addition of
the primary colors of light
• TV screen made up of tiny dots of red,
blue and green
• Each dot glows when hit by an electron
beam
• The colors given off by the glowing dots
add together to produce all the colors on
the screen             EQ: How does light interact with
matter?
Mixing Colors of Pigment
• Pigment – a material that gives a
substance its color by absorbing some
colors of light and reflecting others
• Almost everything contains pigment
– Chlorophyll – plant pigment
– Melatonin – gives us our skin color

EQ: How does light interact with
matter?
Color Subtraction
Mixing pigments is called
color subtraction
• Primary pigments:
yellow, cyan, and
magenta
– They can be combined
to produce any color
– Every color in your book
was produced by using
the primary pigments
and black ink (used for
contrast)                  EQ: How does light interact with
matter?
Class Work and Homework
• Fill In                           EQ: How
– What did I learn              does light
– Confused                     interact with
– Say                             matter?

– Read the passage online “Light and Color”
• Answer questions 1-11 Section Review

```
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