1. “A curious phenomenon” is what HJ Round reported in 1907, when he applied a voltage to a crystal of carborundum (silicon carbide, SiC), which in turn “gave out a yellowish light”. This was the first official report of electroluminescence – light emission from a solid-state material directly caused by an electrical power
2. The first visible LED was invented in 1962 by Professor Nick Holonyak who then worked for General Electric
3. Light bulbs shine by incandescence (emitting light as a result of being heated), LEDs by electroluminescence (luminescence produced electrically, especially by the application of voltage)
4. LEDs are driven by DC (direct current), light bulbs are driven by AC (alternating current)
5. LEDs don’t attract as many insects as other traditional light sources as they have very little UV content
6. LEDs are great for horticulture – deep blue (450nm) and hyper red (660nm) provide the light for photosynthesis, and far red (730nm) controls the plant from germination to vegetative growth and flowering.
7. Good quality LEDs (such as Osram) can easily have a lifetime which exceeds 50,000 hours
8. More and more councils changing over their streetlights to LED versions, saving energy and increasing visibility.
9. Blue LEDs can help keep food fresh - they have been proved to have a strong antibacterial effect on major foodborne pathogens, and are now being used in fridges.
10. The Times Square Ball in New York (dropped every New Year) is illuminated with 32,256 individual LEDs!
1st Image- "Carbonfilament" by Ulfbastel - Own work (own photo). Licensed under CC BY-SA 3.0 via Commons - https://commons.wikimedia.org/wiki/File:Carbonfilament.jpg#/media/File:Carbonfilament.jpg
2nd image - By Vaishak Kallore (Vaishak Kallore) (Own work) [CC BY 3.0 (http://creativecommons.org/licenses/by/3.0)], via Wikimedia Commons
5th Image - By Susan Serra, CKD from Long Island, USA (222 (2)) [CC BY-SA 2.0 (http://creativecommons.org/licenses/by-sa/2.0)], via Wikimedia Commons
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