The Physics
Factbook
An encyclopedia of scientific essays

Wavelength Range of Visible Light

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Curtis, Barnes. Invitation to Biology: Fifth Edition. New York: Worth Publishers, 1994: 163. "For the human eye, the visible radiations range from violet light, in which the shortest rays are about 380 nanometers, to red light, in which the longest rays are about 750 nanometers." 380–750 nm
Chambers Cambridge. Chambers Science & Technology Dictionary. New York: W & R Chambers Limited, 1940: 914. "light [OPTICS] Electromagnetic radiation with wavelengths capable of causing the sensation of vision, ranging approximately from 4000 (extreme violet) to 7700 angstroms (extreme red)." 400–770 nm
Freudenrich, Craig. How Light Works. Howstuffworks.com "The wavelengths of the light we can see range from 400 to 700 billionths of a meter." 400–700 nm
Lapedes, Daniel. Dictionary of Scientific & Technical Terms: Second Edition. New York: McGraw Hill, 1978: 954. "visible radiation(Phys.).Electromagnetic radiation which falls within the wavelength range of 780 to 380 nm, over which the normal eye is sensitive." 380–780 nm
Cesare, Emiliani. Dictionary of the Physical Sciences. New York: Oxford University Press, 1987: 124. "light1. Visible electromagnetic radiation (λ = 0.40 to 0.72 Ωm)." 400–720 nm

Human beings posses five senses, which include the ability to see, hear, taste smell and feel. The ability to see is by far the most important of the five. Sight allows us to differentiate between things, to know when something is moving towards us or away from us and to react to hazardous conditions before they cause any harm. The ability to see also accounts for that awe we get while looking at the sunset over the blue ocean waters of the white sandy beaches with plenty of tall palm trees and waterfalls and not another being in sight. Our eyes are what allow us to see.

Our eyes are designed to detect a small portion of the electromagnetic spectrum. This part of the spectrum is called the visible light region. The visible light region ranges in wavelengths from about 380 or 400 nm to 700 or 780 nm depending on which source is used. In fact it also depends on the sensitivity of a specific persons eyes.

Light waves travel at very high speeds and are absorbed or reflected by various objects. If all the waves are absorbed and none reach our eye then we do not see anything and the image before us appears as having the color of black. If the object reflects all wavelengths of light equally then the object appears to be the color of white. If an object on the other hand reflects light of certain wavelengths but absorbs others then the color of the object will match the wavelengths that are reflected. Every wavelength of light corresponds to a color which was assigned by people for easier recognition. The longer wavelengths appear as red while the shorter visible wavelengths appear as blue or violet.

Pavel Borodulin -- 2002

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