Colors in Nature
Dispersion of Light in a Prism
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Colors separate
Violet has the highest ƒ
(shortest λ), therefore it
disperses the most
because it interacts the
most with the glass
molecules.
Dispersion- the
separation of white light
according to its colors
(frequencies)
The Atmosphere Surrounding the Earth

Light travels through
millions of meters of
nothingness until it
starts to encounter the
earth’s atmosphere

Gas Composition of
Earth's atmosphere:

Nitrogen -78% of
atmosphere
Oxygen - 21% of
atmosphere
Trace gases -1% - Neon,
Helium, Hydrogen,
Methane,
Carbon Dioxide

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What happens to sunlight when it first
encounters Nitrogen and Oxygen
molecules
The Surface of the Moon (where there is
no atmosphere)
Scattering of Light by Molecules
(Why the Sky is Blue)

Nitrogen and Oxygen are
relatively small molecules.
The lower frequencies of
light (red, orange, yellow)
are not affected by the tiny
molecules. Violet gets
scattered the most, indigo
next and then blue. Our
eyes are more sensitive to
blue, so we see the sky as
being blue, not violet.
Why are Sunsets and Sunrises OrangishRed?
How are Rainbows Formed?

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Recall: Dispersion
2 Conditions needed
for a rainbow
1) Sun in one part of
the sky
2) Rain in another part
of the sky
….and You in Between!
According to one unknown child……….
COLOR
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The Color Spectrum…
All color is a derivative of
white light!!
Vocabulary
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Dye – a molecule that absorbs certain
wavelengths of light and transmits or reflects
other.
Pigment – (like dye only larger) is a colored
material that absorbs certain colors and
transmits or reflects others
Color vs. Pigment
Color by

Addition (Light)

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Add all colors of light… get white
Subtraction (Pigment)
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Dye absorbs certain wavelengths…
That is to say it “subtracts” them
Add dye… subtract color
Primary Colors
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Primary Colors – They lied!
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RED
GREEN
BLUE
Secondary Colors
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Cyan
Magenta
Yellow
Primary Pigments

Primary Pigments

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Cyan
Magenta
Yellow
Secondary Pigments
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RED
GREEN
BLUE
Homework
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Read 28.1 – 28.6
Complete Page 12 of Packet.
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(Do NOT do # 26)