Toolbox | Causes of Color

A page from the "Causes of Color" exhibit...

A colorful toolbox

Understanding the colors in our world

Color is a great way to connect students with science. The perception of color is the interplay of the biological (sensing wavelengths of light via nerve cells) and the physical (the physical processes that cause different wavelengths of light).

This exhibit covers all aspects of colored light - from rainbows to light bulbs. Various topics, like aurora, blue sapphires, butterfly wings, and melanin are all explained in detail with an eye to the biology and chemistry behind these phenomena.

Overview of the exhibit

Causes of Color is structured as an informative reading experience and an ideal teaching tool. There are four major sections:

  • Colors are “made” by new photons of light being created. Topics include: incandescence, fluorescence, fire, lightning, fireworks, vapor lamps, chemiluminescence, bioluminescence, mechanoluminescence, auroras, and Cerenkov radiation. Glowing gases, burning fuels, mixing chemicals, and moving electrons all produce light of a specific color.
  • Colors originate when some photons are “lost,” and what we see is the remainder of the light. Topics include: water, ice, glaciers, bacteria, metals (like gold), semiconductors, blue diamonds, LED lamps, photoluminescence, red rubies, green emeralds, blue sapphires, amethysts, quartz, chlorophyll, and anthocyanins. Parts of the light are eliminated and you see only a fraction of the whole light wave, that is, a specific color.
  • Colors originate when some wavelengths are “moved” differently than others, causing certain wavelengths to be seen. Topics include: rainbows, dispersive refraction, scattering, interference, iridescence, and holograms. Light waves can be bent and bounced and reflected, and these phenomena produce different colors.
  • “Vision” includes explanations of colorblindness, colors for animals (such as birds and horses), early studies of color, and representations of color and melanin. A history of color is delineated and how color is perceived is explained.

Most sections of the exhibit have “do it yourself” pages with instructions for students to do at school or at home. These exercises take learning to the next level through hands-on exploration of the ideas in the section.

For a more neurological spin on color, please see the companion WebExhibit, “Color Vision and Art,” which is more focused on the neurobiology of color and its relation to art though the ages.

Useful tool for teaching on multiple levels.

Causes of Color is helpful for students in middle school, high school, and college, as well as adult learners.

College courses

College students find the detailed explanations of colors throughout the exhibit accessible and thorough. The DIY activities lend themselves to a greater understanding of the principles behind the colors. The Melanin section is a meticulous treatment of the topic and how it applies to our skin type. The Gemstones section is a metallurgical essay about colors and chemicals. Discussions of the eye, mind, and colorblindness are as good an explanation as offered by any textbook.

A General Biology class may be interested in cyanobacteria that color the Red Sea; and the double bond in carbon atoms that causes green chlorophyll. The cone cells in the retina let us see color; absent cone cells result in colorblindness. Vision in the animal kingdom is addressed and explained.

A General Chemistry class can learn about the vibrational energy of hydrogen bonds that give water its blue color. Band theory explains the color of metals and semiconductors, as well as the blue color of the Hope diamond. The porphyrin of magnesium and nitrogen is the basis of chlorophyll, an organic molecule. Other chemicals are responsible for emitting light, such as those in glow sticks and fireflies.

A General Physics class can learn about Max Planck’s black body radiation and his understanding of the quantum nature of matter. They can gain an understanding of the gas excitations that produce signature emission line spectra; the mechanism of sodium and mercury vapor lamps; and the Cerenkov radiation seen in water pools in nuclear reactors. Dispersive refraction explains rainbows and green flashes from the sun; scattering of light waves contributes to the color of the sky and sunsets; interference of light waves causes iridescence in animals, such as crustaceans, seashells, and pearls. Holograms, as seen on credit cards and driver’s licenses, are the result of interference of light waves,

An Earth Science or Geology class can learn about the orbital energies of electrons and the resultant color of gemstones, such as emeralds, rubies, and sapphires. They can read about the solar wind and its effect on earth – the Aurora Borealis and Aurora Australis.

High School

For high school students, there are distinct biology, physics, environmental and chemistry applications. A biology class can spend time on the structure and function of the parts of a human eye, the structure of chlorophyll and aspects of melanin, and color blindness. Biology classes may also find our exhibit about color vision and art interesting, especially the background information pertaining to ”What is Color?”

A Physical Science class can spend time on the electromagnetic spectrum and the relationship between frequency and wavelength, as well as the laws of reflections and refraction. Environmental Science classes can study in detail the history of artificial lighting with an emphasis on compact fluorescent light bulbs. A Chemistry class can study electrons and bonding and its relationship to color. Art classes can study the history of the color wheel and the difference between mixing lights and mixing paints. Art classes may also find our exhibit about color vision and art interesting, in particular the Marilyn Monroe color changer.

Middle School

Middle school teachers and students can find relevance at the web site in the DIY activities, and the photographs and explanations of light as seen in bubbles, a sunset, a CD or DVD, and gemstones. Middle school students are curious and energetic, and the activities channel that enthusiasm and expose them to new scientific principles. Focusing on the history of color allows students to explore different patterns of color arrangements. Causes of Color keeps students busy.

Adult Learners

Anyone interested in age-old questions like, “Why is the sky blue?” or “Why is the grass green?” can find the answers in this WebExhibit. You can take a colorblindness test, learn about auroras, and gain an understanding of the role electrons play in color. Whether you want to understand how the eye works and why you need glasses, why the sky gets so red at sunset, or how rainbows can be so beautiful, Causes of Color provides the answers.

Ready to get started?

» See a list of lesson plans.

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