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Phosphorous : The bringer of Light

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Man invented fire ages ago and till date, fire is an indispensable aspect of our everyday life. Right from cooking to light, we use fire directly or indirectly. We use matchsticks for lighting the lamp and also for many other things. The matchsticks have phosphorus and let us now find out more about phosphorus....  Phosphorus: The Bringer of Light Ever since man discovered fire, it has been an indispensable aspect of our everyday life. Wondering what phosphorus has to do with fire? Keep reading... Let there be Light (Phosphorus) Phosphorus has the ability to ignite readily and hence is used as the main constituent in the heads of matches. It smoulders in air, and when it is warmed, it bursts into flames thereby producing thick, acidic smoke. In the late 17th century, a German alchemist named Hennig Brandt heated the solid residue that was formed by the evaporation of urine. The distilled vapour glowed in the dark. As a result of this observation, Brandt named...
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Why the sky is blue?

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Why the sky is blue? We all can look up to the sky and see its beautiful blue colour. Why is it blue, and not red, or white for instance? As I commented in the "Vegetables post", an object is coloured because of the light that it reflects. The white light from the sun contains all the wavelengths, but when it impacts on an object some of its wavelengths are absorbed and some reflected. For example blue objects reflect 'blue' light, which is light with a pretty short wavelength. There is a phenomena named Rayleigh scattering , that consists on the scattering of light by particles much smaller than its wavelength. This effect is especially strong when light passes through gases. Each of the wavelengths of light suffers a different scattering when it encounters the gas particles that form the atmosphere (nitrogen, oxygen...). This effect is more prominent in the case of short light wavelengths, that are the blue end of the visible spectrum, so the...
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