Why is the sky blue? Why is the setting sun red? Why is deep water blue or green?
Well, the cause in each is the scattering of light- a diffraction effect. Dust particles and even the molecules of atmospheric gases interrupt the wave fronts of sunlight advancing to the atmosphere. The light that was advancing in a straight line from the sun to the Earth is dispersed. Tiny new wave fronts develop in all directions. In a new word, the light is scattered.
To begin, the white light we see is really made up of many different colors of light. You can see these when light is passed through a prism. The color band formed when light passes through a prism is called a spectrum. The band colors are red, orange, yellow, green, blue, indigo, and violet. These are the colors of the rainbow. These colors are visible light, light that humans can see.
During the early times of man's civilization speculation about light was widespread. Hindus and Greeks conjectured that light is a stream of matter emanating from the object perceived. Also Democritus hypothesized that light is a stream of particles having well defined properties and that color is not one of them. On the contrary, the Platonists subsequently evolved a rather elaborate conception of vision in which three streams of particles originating from the sun, the object and the eye fill together and return to the eye.
The corpuscular theory by Sir Isaac Newton
…explains that light is tiny particles called corpuscles sent out by luminous bodies and which behave like tiny elastic balls. The bouncing of these balls explains the reflection of light. This theory was not favored by most scientists on the ground that it cannot explain refraction of light.
The wave theory of Christian Huygens
…asserts that light is a form of wave motion sent out by luminous bodies. Huygens assumed that all spaces, molecular and interplanetary are filled with a hypothetical medium known as ether.
The quantum theory by Max Planck
…advanced the idea that light is an energy called photons or quanta which are transmitted in small bundles or quantities from luminous bodies and which, upon entering the eyes, makes us able to see.
The theory of relativity by Albert Einstein
…doubts the existence of the ether, but it admits the idea of the corpuscular theory and certain phases of the wave theory.
In 1666, Isaac Newton embarked an experimental study of light and presented the theory of color as we know it today that white light is a mixture of all colors and that objects appear to have color because they reflect into the eyes more of some components of white light than of others.
It was not until the beginning of the 19th century that Thomas Young and Augustin Fresnel established a detailed wave theory of light capable of answering Newton's objections and explaining in as simple and convincing way almost all the optical phenomenon then known.
The electromagnetic theory by James Clark Maxwell explains that light is the result of the oscillations of the electrically charged particles of the atoms.
And since we are on it, light is a word used variously to denote the sense impression received by the eye and the agent that produces this impression. These may be termed to its subjective and physical aspects. As a form of energy that travels freely through space, it is considered as an electromagnetic radiation just like radio waves, infrared radiation and x-rays. We can see only the part of the range of electromagnetic radiation. The part we can see is light.
Thus, one of the tools that professional camera operators is a color filter. A color filter is a thin piece of film that removes all colors except the color of the filter. Red filters are red because they absorb all the different colors of the spectrum except red. The red is reflected back to your eye. Blue and green filters work the same way. When all of the colored light is filtered out, you can see only black.
The Long and Short of It
Using improvised color filters, the researcher established how theater crews transform a room into different specific moods to make it scary or dark among others.
Using color filters, lighting in a theater chamber or room is mobilized. Depending upon the layout of the set or the emotion that the production staff together with its director light is varied from turning it into blue to red; from red to green; and green to yellow; and even to black.
Color filters are widely used not only in theaters but also in camera which adds effects to pictures being taken. It either intensifies the shade of a background in a photo or create something odd to a picture which ordinary lenses couldn't create.
The visual effects these filters produce depend upon stimuli affecting the retina and other structures of the eye. Many subtle peculiarities of color vision involve the complex processes by which visual sensations are interpreted in the brain. Among them are harmony or discord of colors, the effects of adjacent colors on each other, and the influence of colors upon emotional moods.
Colors can deceive the eyes in many ways and visual judgments of color are very rough. They tell only the predominant behavior at the surface of an opaque object. For example, red walls seem nearer than blues. This effect seems to depend upon the way in which the eye accommodates to radically different wavelengths. Certain more or less definite emotional effects are produced by colors. Green is restful, while red is exciting and disturbing. These two colors have long served for traffic signals.