Teacher's Notes
Subject: Physics
Topic: The Behavior of Light and Color
Grades: 7­9
Prior Knowledge: Light can act as a wave or particle. White light is composed of seven colors: red, orange, yellow, green, blue, indigo and violet. Colors are due to wavelengths. A prism bends them to different angles according to wavelength.
Light and Colors
Lesson Objectives
By the end of this lesson student’s should understand and be able to demonstrate
three ways light behaves as it strikes surfaces
•
why objects appear to be certain colors, and •
how filtered light can affect their appearance
how the three primary colors of light interact to •
make all the colors we see. Teacher's Notes
Lesson Notes
Many people do not realize that the primary colors of light are red, blue and green. The combination and intensity of these colors of light create all the color we see.
A combination of all primary light colors makes white (all wavelengths combine) and an absence of light makes black.
Most people are more familiar with the primary colors of pigments. Paints and dye are not a source of light so they behave in a light reductionist manner. The primary pigment colors are magenta, cyan and yellow. Cyan is a turquoise like color. If all these colors are combined the result is black (all wave lengths are absorbed by more and more pigments). The absence of pigment is white. Major lesson points:
Understand that white light is composed of a spectrum of colors: ROYGBIV
•
Explain that light is transmitted, absorbed or reflected when it strikes a surface.
•
Describe the differences between transparent, translucent and opaque
•
Explain why objects appear to have certain colors and the effect of colored •
light on colored objects
Describe how the primary light colors combine to make other colors.
•
Lesson Objectives
White light is composed of seven colors: red, orange, yellow, green, blue, indigo and violet.
Tap the sun and use the markers below to
identify the colors on the rainbow.
Lesson Notes
What happens when light strikes the surface of an object?
Discuss and pull the tabs to learn more.
When light strikes any form of matter the light can be:
Transmitted
Transmitted
Light that passes through the substance it strikes. If transmitted readily the substance is transparent. If some light is scattered the substance is translucent. Absorbed
Absorbed
If light is absorbed, it enters the object as heat energy and the substance is considered opaque.
Reflected
Reflected
If light bounces off a surface or is reflected the object will appear to be opaque. ed of seven colors: red, orange, yellow, green, blue, indigo and violet.What happens when light strikes the surface of an object?
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Light Transmission
Drag the correct answer to the appropriate space
to complete the sentences.
Light Transmission
Black and White
Touch the question to answer.
Why do objects appear to have color?
Follow instructions on each slide below.
Why do objects appear to have color?
What if the light shining on an object is not white?
Tap on the bulbs and write your observations.
yellow+purple = brown
green + red = black
blue + green = purplish blue
Black and White
Light that is filtered makes objects appear different.
What would the world look like through tinted glasses? Tap on each color button.
What if the light shining on an object is not white?
The primary colors of light are red, blue and green. When mixed, these create all other colors. Touch the colored theater spotlights to find out what light mixtures makes.
Light that is filtered makes objects appear different.
The primary colors of light are red, blue and green. When mixed, these create all other colors. 2
Review Question Review Question Write your answer.
Drag the word to fill in the blanks.
What color(s) of light is/are absorbed by a blue bird?
Transparent
1) Air is _____________. 2) Metal is ____________. Opaque
3) Glass is ____________. Transparent
4) Wax paper is ___________. Translucent
Opaque
5) Wood is ____________. All colors except blue.
Translucent
Transparent
Review Question
Opaque
Review Question
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Review Question What color(s) of light is/are reflected by an orange?
Color in or circle the primary colors of light.
Red
Orange
Blue
Green
red light
B
blue light
Red Green
Yellow
A
C orange light
Blue
D
Review Question
2
Light creates heat. What color would be better to wear at the beach, black or white? Why?
yellow light
Indigo
Violet
Review Question
3
Light creates heat. For roofs in hot or cold climates what color would be better,
black or white?
A
black
A
hot: black , cold: black
B
white
B
hot: black , cold: white
C
hot: white , cold: white
D
Review Question
cold: black , hot: white
Review Question
3
4
What color is transmitted
by a red piece of glass?
5
What happens when the primary colors of light are mixed equally?
A
red
A
Black light is produced.
B
blue
B
Blue light is produced.
C orange
C
Red light is produced.
D
D
yellow
Review Question
6
Why would a white cloud reflect orange light?
White light is produced.
Review Question
7
Why would a yellow banana appear black under violet light?
A
White reflects any and all light.
A
It reflects violet light.
B
White reflects only orange light.
B
It absorbs violet light.
Review Question
Review Question
The End
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