Light spectru

Color – (or Colour) is the visual perceptual property corresponding in humans to the categories called red, yellow, blue and others. Color derives from the spectrum of light (distribution of light energy versus wavelength) interacting in the eye with the spectral sensitivities of the light receptors. Color categories and physical specifications of color are also associated with objects, materials, light sources, etc., based on their physical properties such as light absorption, reflection, or emission spectra.


Color (images) – combining photos with physics principles to explain how we see our physical world in color.

Rainbows (images) – Two things are required for the formation of a rainbow – suspended droplets of water and bright light. The water droplets, whether from the mist of a sprinkler, the splash of a waterfall, or atmospheric condensation following a storm, are essential. Light, usually from the sun, enters these drops as white light and emerges as a rainbow of colors. The phenomenon is referred to as dispersion – the separation of white light into its component colors.

Is Your Red The Same as My Red? (video 9:35) –

Animated traffic light

What’s the problem?
Color blindness – a color vision deficiency in animals, is the inability to perceive differences between some of the colors that others can distinguish. It is most often of genetic nature, but may also occur because of eye, nerve, or brain damage, or due to exposure to certain chemicals. The English chemist John Dalton in 1798 published the first scientific paper on the subject,

  • Ask – Why is color blindness important to engineers? What are some of the “signals” that depend on color? What’s the problem if some people can’t tell what color something is?
  • Imagine – There are many ways to communicate important information visually without using color. Shape and location work. What are some other design ideas?
  • Plan, Create – What are some of the ways that engineers use to compensate for users who are color blind? What are other ways to make things different besides color?
  • Improve – What would be necessary to “cure” color blindness?

Engineering ideas

  • color, value, shade, pigment, reflection, absorption, spectrum, spectroscopy, dispersion

Do It
Challenges for you to work on…

  • Color vision – interactive – Make a whole rainbow by mixing red, green, and blue light. Change the wavelength of a monochromatic beam or filter white light. View the light as a solid beam, or see the individual photons.
  • Color Uncovered (interactive simulations, app, free) – lots of cool color-related topics to explore. Learn why friends shouldn’t let men buy bananas. Try your own color experiments using simple items you have at home: a CD case, a drop of water, and a piece of paper. Discover how digital devices create color. Find out what causes afterimages—and more.

Learn more…