<Li> Near - infrared, from 120 to 400 THz (2,500--750 nm). Physical processes that are relevant for this range are similar to those for visible light . The highest frequences in this region can be detected directly by some types of photographic film, and by many types of solid state image sensors for infrared photography and videography . </Li> <P> Above infrared in frequency comes visible light . The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light . By definition, visible light is the part of the EM spectrum the human eye is the most sensitive to . Visible light (and near - infrared light) is typically absorbed and emitted by electrons in molecules and atoms that move from one energy level to another . This action allows the chemical mechanisms that underlie human vision and plant photosynthesis . The light that excites the human visual system is a very small portion of the electromagnetic spectrum . A rainbow shows the optical (visible) part of the electromagnetic spectrum; infrared (if it could be seen) would be located just beyond the red side of the rainbow with ultraviolet appearing just beyond the violet end . </P> <P> Electromagnetic radiation with a wavelength between 380 nm and 760 nm (400--790 terahertz) is detected by the human eye and perceived as visible light . Other wavelengths, especially near infrared (longer than 760 nm) and ultraviolet (shorter than 380 nm) are also sometimes referred to as light, especially when the visibility to humans is not relevant . White light is a combination of lights of different wavelengths in the visible spectrum . Passing white light through a prism splits it up into the several colors of light observed in the visible spectrum between 400 nm and 780 nm . </P> <P> If radiation having a frequency in the visible region of the EM spectrum reflects off an object, say, a bowl of fruit, and then strikes the eyes, this results in visual perception of the scene . The brain's visual system processes the multitude of reflected frequencies into different shades and hues, and through this insufficiently - understood psychophysical phenomenon, most people perceive a bowl of fruit . </P>

Visible light which has a wavelength of between 380 nm and 760 nm is usually