Light Sources and Lighting: from Technology to Energy Savings
Résumé
Man has always desired to carry on with his normal life after nightfall. Subject to the rhythms and hazards of natural light sources, he very quickly tried to replace the natural light with artificial sources. For centuries, human society had to satisfy itself with the use of fire to generate light. Man thus, unconsciously, discovered one of the two processes of artificial light generation: incandescence. However, phenomena such as phosphorescence and fluorescence have shown that material was able to generate light without necessarily increasing its temperature. Man also desired to imitate other “natural” light sources such as fireflies, phosphorescent minerals or lightning. These sources generate light thanks to the luminescence 1 phenomena. This second process is much more efficient than incandescence, but was previously not exploitable because these sources were either hazardous or difficult to control. Furthermore, the energy efficiency was not up to date. However, during this period, man always had a dream of putting lightning into a bowl to give out light. It was only during the 19th century that this dream came true. The English chemist Sir Humphry Davy (1778–1829) discovered the electric discharge phenomena. In 1802, he tried to reproduce in his laboratory Franklin’s experiment demonstrating the electric nature of lightning.
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