LAMP at Tutankhamen? The interiors of the Egyptian pyramids - tombs of the Pharaohs - were finished, painted murals, when construction is nearing completion. But could not the same artists work in the dark! However, neither on the walls or ceiling of tombs that have no windows, no smoke - signs of torches or oil lamps. Had the ancient Egyptians used electric lights? What excavated in Mesopotamia design, similar to modern battery cells can not reject this idea as absurd. But this fact has not yet been verified. So officially the beginning of electric lighting era considered in 1872, when our compatriot AN Lodygin invented the light-bulb. In 1879, the famous American inventor Edison T., sorting through thousands of choices laid the foundation for mass production fixtures for electric lamps with carbon filament. Then it took many years of hard working professionals around the world to gradually light bulbs purchased with a familiar look filled with an inert gas glass bulb that glows inside the heated metal spiral shock.
Light and heat. All the best-known today, sources of light - fire, a candle, a kerosene lamp, gas lamp, light bulbs - have basically the same principle of heat radiation. Patterns of thermal radiation is known to be described by laws of Kirchhoff and Planck. By law, Kirchhoff's heated body can radiate only such length and frequency, which at a given temperature it can absorb. Quantitative characteristics of the radiation intensity, its spectral characteristics and temperature dependence are determined by Planck's law. If body absorbs virtually all the radiation incident on it, it is called a blackbody, and its radiation is characterized by a continuous spectrum. In nature, there is absolutely black bodies, but this concept is very convenient for theoretical calculations.
The rest of the body actually existing, called gray. Their emission spectrum is very far from solid. "AS ONCE Jacques ringer ..." Yes continuum radiation in most cases we do not need it.