visible light which has a wavelength of between 380 nm and 760 nm is usually
detected by the human eye
title: Light text: Light Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is the visible spectrum that is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10 to 7.00 × 10 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz). The main source of light on Earth is the Sun. Sunlight provides the title: Visible spectrum text: Visible spectrum The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz. The spectrum does not contain all the colors that the human eyes and brain can distinguish. Unsaturated colors such as pink, or purple variations like magenta, for example, are absent because they can only be made from a title: Visible spectrum text: be detected in astronomical objects by emission lines and absorption lines. The shifting of spectral lines can be used to measure the Doppler shift (red shift or blue shift) of distant objects. Visible spectrum The visible spectrum is the portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 700 nanometers. In terms of frequency, this corresponds to a band in the vicinity of 430–770 THz. The spectrum does not contain all title: Electromagnetic radiation text: a form of electromagnetic radiation with wavelengths ranging from as long as one meter to as short as one millimeter; with frequencies between 300 MHz (0.3 GHz) and 300 GHz. Natural sources produce EM radiation across the spectrum. EM radiation with a wavelength between approximately 400 nm and 700 nm is directly detected by the human eye and perceived as visible light. Other wavelengths, especially nearby infrared (longer than 700 nm) and ultraviolet (shorter than 400 nm) are also sometimes referred to as light. The basic structure of matter involves charged particles bound together. When electromagnetic radiation impinges on matter, title: Optical radiation text: Optical radiation Optical radiation is part of the electromagnetic spectrum. It is subdivided into ultraviolet radiation (UV), the spectrum of light visible for man (VIS) and infrared radiation (IR). It ranges between wavelengths of 100 nm to 1 mm. Electromagnetic waves in this range obey the laws of optics--they can be focused and refracted with lenses, for example. Optical radiation may be produced by artificial sources, such as UV lights, common lightbulbs, and radiant heaters, but the primary source of exposure for most people is the sun. This exposure can result in negative health effects. All wavelengths across this range