Instructional Kit: Light, Color & Lasers
Light and Color
Mathematics & Science Center Staff
Funded by the Mathematics & Science Center
Major
Understanding
As part of the electromagnetic spectrum, white light is a mixture of the many
colors of visible light. Each color of visible light represents a different
wavelength with red light being the longest and violet light the shortest. The
arrangement of the colors that make up white light is called the spectrum of
visible light. When white light passes from one medium to another, such as
from air through a glass prism, each wavelength of light bends and separates
so that each color of the spectrum can be seen. A red color filter absorbs all
light except red light. A green color filter absorbs all light except green light.
Background
Information
For more information on the color spectrum and color filters, go to the book,
Stop Faking It! Light, which is provided in the kit. Go to Chapter 2,
“Colorful Waves”.
Standards of
Learning
Virginia Standards of Learning: Science 5.1, 5.3
National Science Education Standards:
Level K-4 Physical Science (Light, heat, electricity, and magnetism)
Level 5-8 Physical Science (Properties and changes of properties in matter)
Safety
Do not look directly at the sun through the red or green color filters or
diffraction grating.
Time
Viewing the spectrum
Using the color filters
Vocabulary
Color spectrum: The colors of visible light from the longest wavelength to
the shortest wavelength.
ROY G BIV: An acronym to help students remember the order of the colors
in the spectrum. (red, orange, yellow, green, blue, indigo, violet)
Absorb: To “soak up” light
Reflect: To “bounce back “ light
Refract: To “bend” light
Transmit: To allow a particular wavelength of light or a certain color to
“pass through”
Materials Needed
For the class:
Projector, “Mag” flashlight or other bright light source
Prisms
Water prism
Diffraction Grating
Light, Color & Lasers
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15 minutes
15 minutes
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For each student:
Red color filter
Green color filter
Red and Green posterboard cards.
1 sheet of white paper
Markers: red, green, blue
Procedures
1. Shine a bright light source through one of the prisms provided in the kit
so that the spectrum of visible light is projected on the wall or ceiling of
the classroom. Or, fill the water prism with water and place it on a sunny
windowsill, if available. A beautiful spectrum will be produced! The
water prism can also be used on an overhead projector.
2. Explain that as white light passes through the prism, each wavelength of
light bends at its own angle producing the color spectrum. Introduce the
acronym ROY G BIV as a “name” that will help the students remember
the colors of the spectrum. Each letter in the “name” represents the order
of the colors of the spectrum: red, orange, yellow, green, blue, indigo,
violet.
3. Pass out a red and a green color filter to each student.
4. Have them view the spectrum through each filter. How does a color filter
affect the color spectrum? The red filter only allows red light to transmit
or pass through the filter so only the red color of the spectrum can be
seen. The green filter only allows green light to pass through so only the
green color of the spectrum can be seen.
Light, Color & Lasers
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5. Have the students look at objects in the classroom through the color
filters. Discuss how the filters affect the colors of the objects.
6. Give each student a red and green posterboard card to view through the
red and green color filters. How do the cards look through the red filter?
The red card appears red because the red filter allows red light to pass
through the filter. However, the green card does not look green because
the red filter absorbs the green light and the card looks gray. The
reverse occurs when the cards are viewed through the green filter. The
green card looks green, but the red light is absorbed and the red card
looks black or dark gray.
Extensions
1. Give each student a blank sheet of white paper.
 Have the student write a “secret message” (one simple sentence) on
the paper with a blue marker.
 Next, have the students write another sentence over the first sentence
with a red marker so that the original sentence is disguised or
obscured by the red lettering. Or, the students could put symbols or
numbers over the original sentence to obscure the lettering.
 Have the students trade papers and view the “secret message”
through the red color filter. Can the “secret message” be read?
 The red color filter will absorb the blue light so that the letters in the
“secret message” appear black. The red color filter will transmit red
light, so the “secret message” appears to be black lettering on a red
background.
 View the “secret message” through the green color filter. Does it
stand out? The green filter absorbs both the red and blue light so that
the “secret message” still appears scrambled.
 Repeat the activity with red and green markers.
 Repeat the activity with blue and green markers.
2. Distribute the mounted diffraction grating to the students.
 Students may hold the diffraction grating close to one eye and look
through it at different light sources. They will see rainbows! This
diffraction grating is made of plastic in which many fine lines have
been etched. The effects are similar to that of the prism. As white
light passes through the diffraction grating, its waves are refracted
or bent by the fine lines so that the color spectrum can be seen.
 Be sure to hold the diffraction grating by the mounted frames. Avoid
touching the plastic with the fingers as oil from the skin will destroy
the refractive effects of the plastic.
Teaching Tips
Light, Color & Lasers
Although this activity is not typically done outside, warn the students about
the dangers of looking directly at the sun through diffraction grating or color
filters. Sunlight contains all the colors of the spectrum, but it also contains
shorter, invisible light waves (ultraviolet) that can burn the skin or the retina
of the eye. A “sunburned” retina can be permanently scarred resulting in
blindness. Never look directly at the sun through diffraction grating or
color filters!
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Assessment
1. At a learning station, place the color filters (red and green) and a variety
of objects for students to examine through the filters. Examples: red
apple, red cherry, yellow banana, green grapes, orange, brightly colored
toys such as cars and yoyos.
2. Students look at the objects through each filter and write a sentence to
explain what they observe.
3. Go to http://rubistar.4teachers.org/rubistar/ to construct a rubric to assess
student understanding of how color filters work.
Light, Color & Lasers
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© Mathematics & Science Center 2006
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