Have you ever experimented looking through a prism and seen a continuous range of colors, just like the rainbow in the sky. Have you ever pondered over this subject as to where these different colors come from? Well, these colors are called spectral colors (known as the visible spectrum). These separate spectral colors, seen through a prism or in a rainbow produced by visible light, are composed of a single wavelength (monochromatic light), which gives out pure spectral colors. A color spectrum or display of light or radiation are separated by wavelength. Light visible to humans is just a minuscule part of the electromagnetic spectrum, which also consists of infrared, ultraviolet, and x-ray waves.
What is Color Spectrum Wavelength?
In olden days, it was thought that color was a mixture of light and darkness and the prisms actually colored the light. Fortunately, this theory has been upgraded after the discovery of electromagnetic phenomena. All the colors that we perceive usually differ depending upon the wavelength of the light that we see. The major reason why human eyes comprehend colors is because there are specific wavelengths of light that stimulates the retina of our eyes.
This is why we see colors. The progression of the wavelength is from long wavelength as red to short wavelength as violet. It is commonly expressed in terms of nanometers [1 nm = 10-9 m]. The range of wavelength of visible light is approximately from 750nm (red end) to 450nm (violet end). Although the spectrum is continuous, these ranges are used as an approximation, with unclear boundaries between one single color and the next.
The Man Behind this Theory
Although Roger Bacon had earlier discovered the visible spectrum by experimenting with a glass of water, the most former explanations of optical spectrum came from Sir Isaac Newton, from two of his theories; Opticks and Goethe -- Theory of Colors. The color circle of Newton's theory from Opticks showed the correlation of the colors with musical notes.
The spectral colors are arranged from red to violet separated by the notes of the musical scale. This circle spanned a full octave, from D to D. This diagram is a big help to understand the basics of this theory. It passes from one end of the spectrum, i.e. red, to the other end, i.e. violet, reflecting the concept that when violet and red lights are mixed, non-spectral purple colors are seen. Isaac Newton divided the color spectrum into seven different colors namely; red, orange, yellow, green, blue, indigo and violet, famously known as (VIBGYOR). This is the reason why, the wavelengths are different for each of these colors.
Shorter wavelengths of visible light are known to be in the ultraviolet range (violet color) whereas, longer wavelengths are known to be in the infrared range (red color). It is impossible for a human eye to see any of these ranges.