Color

Primary Colors
The human eye is sensitive to a narrow band of electromagnetic radiation that lies in the wavelength range between 400 and 700 nanometers, commonly known as the visible light spectrum, which is the only source of color. When combined, all of the wavelengths present in visible light, about a third of the total spectral distribution that successfully passes through the Earth's atmosphere, form colorless white light that can be refracted and dispersed into its component colors by means of a prism. The colors red, green, and blue are classically considered the **primary** colors because they are fundamental to human vision. Light is perceived as white by humans when all three cone cell types are simultaneously stimulated by equal amounts of red, green, and blue light.

Reflection of Light
Reflection of light (and other forms of electromagnetic radiation) occurs when the waves encounter a surface or other boundary that does not absorb the energy of the radiation and bounces the waves away from the surface. The simplest example of visible light reflection is the surface of a smooth pool of water, where the light is reflected in an orderly manner to produce a clear image of the scenery surrounding the pool. Throw a rock into the pool, and the water is perturbed to form waves, which disrupt the reflection by scattering the incident and reflected light.