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Light

Light
A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) get separated Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.[1] Visible light is usually defined as having a wavelength in the range of 400 nanometres (nm), or 400×10−9 m, to 700 nanometres – between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).[2][3] Often, infrared and ultraviolet are also called light. The main source of light on Earth is the Sun. Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them. Electromagnetic spectrum and visible light The behaviour of EMR depends on its wavelength. Speed of light Main article: Speed of light Optics Refraction where Table 1.

http://en.wikipedia.org/wiki/Light

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Economic View on Spaghetti Sauce - Research Papers - Angelhula Ted Talks by Malcolm Gladwell on Spaghetti Sauce in term of Economic perspective Gladwell talks about Howard Moskowitz, who was the food industry guru and most famous for re-inventing spaghetti sauce. The key point in this story is basically the destruction of the Platonic Ideal. Prego has hired him to find the perfect spaghetti sauce so as to compete with Ragu. Surrender (military) Muslims surrender to Spain: Boabdil gives the Granada key to Ferdinand and Isabella Ulysses S. Grant accepting the surrender of Robert E. Lee at Appomattox Court House. A white flag or handkerchief is often taken or intended as a signal of a desire to surrender, although in international law it simply represents a desire for a parley that may or may not result in a formal surrender.

Spacetime In non-relativistic classical mechanics, the use of Euclidean space instead of spacetime is appropriate, as time is treated as universal and constant, being independent of the state of motion of an observer.[disambiguation needed] In relativistic contexts, time cannot be separated from the three dimensions of space, because the observed rate at which time passes for an object depends on the object's velocity relative to the observer and also on the strength of gravitational fields, which can slow the passage of time for an object as seen by an observer outside the field. Until the beginning of the 20th century, time was believed to be independent of motion, progressing at a fixed rate in all reference frames; however, later experiments revealed that time slows at higher speeds of the reference frame relative to another reference frame.

Is the US in denial over its $14tn debt? 27 June 2011Last updated at 10:16 By Justin Webb BBC News Is America in denial about the extent of its financial problems, and therefore incapable of dealing with the gravest crisis the country has ever faced? This is a story of debt, delusion and - potentially - disaster. Sunlight The ultraviolet B component of sunlight on the skin is an effective source of vitamin D3 (cholecalciferol) from serum cholesterol. Summary[edit] Sunlight may be recorded using a sunshine recorder, pyranometer, or pyrheliometer. Sunlight takes about 8.3 minutes to reach the Earth from the surface of the Sun. A photon starting at the centre of the sun and changing direction every time it encounters a charged particle would take between 10 000 and 170 000 years to get to the surface.[2] The total amount of energy received at ground level from the sun at the zenith depends on the distance to the sun and thus on the time of year.

Wave–particle duality Origin of theory[edit] The idea of duality originated in a debate over the nature of light and matter that dates back to the 17th century, when Christiaan Huygens and Isaac Newton proposed competing theories of light: light was thought either to consist of waves (Huygens) or of particles (Newton). Through the work of Max Planck, Albert Einstein, Louis de Broglie, Arthur Compton, Niels Bohr, and many others, current scientific theory holds that all particles also have a wave nature (and vice versa).[2] This phenomenon has been verified not only for elementary particles, but also for compound particles like atoms and even molecules. For macroscopic particles, because of their extremely short wavelengths, wave properties usually cannot be detected.[3] Brief history of wave and particle viewpoints[edit]

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Cloud Stratocumulus stratiformis cumulogenitus Clouds in the troposphere, the atmospheric layer closest to Earth's surface, have Latin names due to the universal adaptation of Luke Howard's nomenclature. It was introduced in December 1802 and became the basis of a modern international system that classifies these tropospheric aerosols into several physical forms or categories, then cross-classifies them into families of low, middle and high according to cloud-base altitude range above Earth's surface. Clouds with significant vertical extent are often considered a separate family.

Photon Nomenclature[edit] In 1900, Max Planck was working on black-body radiation and suggested that the energy in electromagnetic waves could only be released in "packets" of energy. In his 1901 article [4] in Annalen der Physik he called these packets "energy elements".

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