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In about 300 BC, Euclid wrote Optica, in which he studied the properties of light. Euclid postulated that light travelled in straight lines and he described the laws of reflection and studied them mathematically. He questioned that sight is the result of a beam from the eye, for he asks how one sees the stars immediately, if one closes one's eyes, then opens them at night. If the beam from the eye travels infinitely fast this is not a problem. [32] Nichols, E.F; Hull, G.F. (1903). "The Pressure due to Radiation". The Astrophysical Journal. 17 (5): 315–351. Bibcode: 1903ApJ....17..315N. doi: 10.1086/141035. Archived from the original on 8 October 2022 . Retrieved 15 November 2020. Visible light" redirects here. For all parts of the electromagnetic spectrum that can be seen by the eye, see Visible spectrum. Light transmits spatial and temporal information. This property forms the basis of the fields of optics and optical communications and a myriad of related technologies, both mature and emerging. Technological applications based on the manipulations of light include lasers, holography, and fibre-optic telecommunications systems.
O'Connor, J J; Robertson, E F (August 2002). "Light through the ages: Ancient Greece to Maxwell". Archived from the original on 19 March 2017 . Retrieved 20 February 2017. Fokko Jan Dijksterhuis, Lenses and Waves: Christiaan Huygens and the Mathematical Science of Optics in the 17th Century, Kluwer Academic Publishers, 2004, ISBN 1-4020-2697-8 The wave theory predicted that light waves could interfere with each other like sound waves (as noted around 1800 by Thomas Young). Young showed by means of a diffraction experiment that light behaved as waves. He also proposed that different colours were caused by different wavelengths of light and explained colour vision in terms of three-coloured receptors in the eye. Another supporter of the wave theory was Leonhard Euler. He argued in Nova theoria lucis et colorum (1746) that diffraction could more easily be explained by a wave theory. In 1816 André-Marie Ampère gave Augustin-Jean Fresnel an idea that the polarization of light can be explained by the wave theory if light were a transverse wave. [37] Léon Foucault carried out an experiment which used rotating mirrors to obtain a value of 298 000 000 m/s [16] in 1862. Albert A. Michelson conducted experiments on the speed of light from 1877 until his death in 1931. He refined Foucault's methods in 1926 using improved rotating mirrors to measure the time it took light to make a round trip from Mount Wilson to Mount San Antonio in California. The precise measurements yielded a speed of 299 796 000 m/s. [17]Plant growth is also affected by the colour spectrum of light, a process known as photomorphogenesis. Liang, Qi-Yu; et al. (16 February 2018). "Observation of three-photon bound states in a quantum nonlinear medium". Science. 359 (6377): 783–786. arXiv: 1709.01478. Bibcode: 2018Sci...359..783L. doi: 10.1126/science.aao7293. PMC 6467536. PMID 29449489. Lynch, David K.; Livingston, William Charles (2001). Color and Light in Nature (2nd ed.). Cambridge: Cambridge University Press. p. 231. ISBN 978-0-521-77504-5. Archived from the original on 8 October 2022 . Retrieved 12 October 2013. Limits of the eye's overall range of sensitivity extends from about 310 to 1,050 nanometers Singh, S. (2009). Fundamentals of Optical Engineering. Discovery Publishing House. ISBN 978-8183564366.
In ancient India, the Hindu schools of Samkhya and Vaisheshika, from around the early centuries AD developed theories on light. According to the Samkhya school, light is one of the five fundamental "subtle" elements ( tanmatra) out of which emerge the gross elements. The atomicity of these elements is not specifically mentioned and it appears that they were actually taken to be continuous. [34] To explain the origin of colours, Robert Hooke (1635–1703) developed a "pulse theory" and compared the spreading of light to that of waves in water in his 1665 work Micrographia ("Observation IX"). In 1672 Hooke suggested that light's vibrations could be perpendicular to the direction of propagation. Christiaan Huygens (1629–1695) worked out a mathematical wave theory of light in 1678 and published it in his Treatise on Light in 1690. He proposed that light was emitted in all directions as a series of waves in a medium called the luminiferous aether. As waves are not affected by gravity, it was assumed that they slowed down upon entering a denser medium. [36] Christiaan Huygens Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves. Our eyes react to light. When we see something, we see the light it reflects, or the light it gives off. For example, a lamp gives off light. Everything else in the room the lamp is in reflects the lamp's light. As the viewer, one cannot directly determine where the ray of light came from prior to reflecting off an object.Use the ruler to join the incident and emergent rays together with a pencil line. This is the refracted ray. Carefully mark in the angle of refraction, r, between the refracted ray and the normal. Seymour: Hello! Seymour Science here… today’s episode is all about where light comes from… with my expert friend, Albert!
Refraction is the bending of light rays when passing through a surface between one transparent material and another. It is described by Snell's Law:
Solar Sails Could Send Spacecraft 'Sailing' Through Space". NASA. 31 August 2004. Archived from the original on 21 October 2012 . Retrieved 30 May 2008. a b Newcomb, Simon (1911). "Light" . In Chisholm, Hugh (ed.). Encyclopædia Britannica. Vol. 16 (11th ed.). Cambridge University Press. p. 624.
The behavior of EMR depends on its wavelength. Higher frequencies have shorter wavelengths and lower frequencies have longer wavelengths. When EMR interacts with single atoms and molecules, its behavior depends on the amount of energy per quantum it carries. Light moves in a straight line. The straight line path is often drawn as a ray. Humans can only see rays of light traveling directly into the eyes. Ray diagrams are used to illustrate light traveling from one place to another. A beam of light can be thought of as a set of light rays. Ohannesian, Lena; Streeter, Anthony (2001). Handbook of Pharmaceutical Analysis. CRC Press. p. 187. ISBN 978-0-8247-4194-5 . Retrieved 20 October 2013. Light and color are forms of analog information. However, electronic cameras and computer displays work with digital information. Electronic cameras or document scanners make a digital version of a color image by separating out the full color image into separate red, green, and blue images. Later, a digital display uses pixels of just those three colors. Computer screens use only these three colors in different brightness levels. The brain puts them together to see all of the other colors in the image.
Light sources
Albert: We call these objects opaque. If light can’t go through an object, it creates a shadow! But sometimes you get special objects that light bounces off… On the other hand, the Vaisheshika school gives an atomic theory of the physical world on the non-atomic ground of ether, space and time. (See Indian atomism.) The basic atoms are those of earth ( prthivi), water ( pani), fire ( agni) and air ( vayu) Light rays are taken to be a stream of high velocity of tejas (fire) atoms. The particles of light can exhibit different characteristics depending on the speed and the arrangements of the tejas atoms. [ citation needed]
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