Aug 29 2007
Image Credits: Nataliya Druchkova/shutterstock.com
Throughout history, there have been many theories looking to explain what color is. Early theories by Aristotle were based around the idea that all colors came from white and black, and were related to the ‘four elements’ but the first theory that laid the foundations of modern optics was provided by Sir Isaac Newton in 1666.
Splitting White Light
Newton passed a narrow beam of sunlight through a prism located in a dark room. Although the sunlight appeared while, on passing through the prism, the white light was split into all the components of the spectrum (red, orange, yellow, green, blue, indigo, and violet) and could be seen on the white screen behind.
People have already seen that light passing through a prism would result in a rainbow-like spectrum, but Newton’s experiments were the first to show that different colors are bent through different angles in the prism. After demonstrating that all the colors we see are part of white light, Newton passed the light through a second prism. Here, all the visible colors were merged again to result in white light.
Source of Color
Our ability to see colors is related to the interaction of light with the colored object. The color of an object is seen because the object reflects, absorbs, and transmits one or more of the colors that make up white light. The endless variety of colors is caused by the interrelationship of three elements: Light, the source of color; the material and its response to color; and the eye, the perceiver of color.
Primary or Additive Colors
There are two main models for using and understanding the interactions between different colors. The first is based on three primary colors, red, green and blue. Colors made by combining blue, green, and red light are called additive; and they are formed by adding different intensities and combinations of the three component colors. The other uses the ‘pigment color primaries’, cyan, magenta, and yellow, which again can be mixed to make new additive colors.
Pigment Colors
Pigments are strongly colored materials that change the color of reflected or transmitted light by absorbing a characteristic color of light. Pigments are found in certain kinds of paints and inks. Differences in the characteristic absorption and light scattering properties between different pigments are why they are available in such a wide range of colors.
Colors of the Visible Light Spectrum
color
|
wavelength interval |
frequency interval |
red
|
~ 630–700 nm |
~ 480–430 THz |
orange
|
~ 590–630 nm |
~ 510–480 THz |
yellow
|
~ 560–590 nm |
~ 540–510 THz |
green
|
~ 490–560 nm |
~ 610–540 THz |
blue
|
~ 450–490 nm |
~ 670–610 THz |
violet
|
~ 400–450 nm |
~ 750–670 THz |
This article was updated on 11th March, 2019.