What is Light-emitting diode?
[[File:RBG-LED.jpg|thumb|right|300px|Blue, green and red LEDs.]] [[File:Arduino led-3.jpg|thumb|Green SMD LED.]] [[File:SiC LED historic.jpg|thumb|A recreation of the first LED to produce visible light, a green LED made from a needle contacting a piece of silicon carbide.]] A '''light-emitting diode''' ('''LED''') is a [[semiconductor]] device that produces light from electricity. LEDs last a long time and do not break easily (compared to [[lightbulb#incandescent|incandescent lightbulbs]]). They can produce many different colors. They are efficient - most of the energy turns into light, not heat.<ref>{{cite web |url=http://green.rpi.edu/archives/greenleds/index.html |title=Greenlighting: a greener world |access-date=2012-05-31 |archive-date=2012-05-14 |archive-url=https://web.archive.org/web/20120514010804/http://green.rpi.edu/archives/greenleds/index.html |url-status=dead }}</ref> An LED is a type of [[diode]] that makes one [[color]] of [[light]] when electricity is sent through it in the expected direction ([[voltage bias|electrically biased]] in the forward direction). This effect is a kind of [[electroluminescence]].<ref>{{cite web |url= http://hyperphysics.phy-astr.gsu.edu/hbase/electronic/led.html |title= Light emitting diode structure}}</ref> The color of the light depends on the [[chemical composition]] of the semiconducting material used, and can be near-[[ultraviolet]], [[Visible_light|visible]] or [[infrared]].<ref>{{cite web |url=http://invention.smithsonian.org/centerpieces/quartz/inventors/biard.html |title=inventors |access-date=2006-06-17 |archive-date=2010-04-01 |archive-url=https://web.archive.org/web/20100401133528/http://invention.smithsonian.org/centerpieces/quartz/inventors/biard.html |url-status=dead }}</ref> The color affects how much electricity is used by the LED. <ref>{{cite web |url=http://www.facstaff.bucknell.edu/mastascu/elessonshtml/Diodes/Diode3.html |title=Light emitting diodes (LEDs) |access-date=2012-05-31 |archive-date=2012-05-11 |archive-url=https://web.archive.org/web