Light from Sand (podcast 2:00) – LEDs or light emitting diodes are everywhere from traffic lights to Christmas ornaments to remote controls. Inside these tiny bulbs is a small grey block which is made of silicon. And, silicon has the unusual origin of coming from sand.
A light-emitting diode (LED) is a two-lead semiconductor light source. Appearing as practical electronic components in 1962, the earliest LEDs emitted low-intensity infrared light. The first visible-light LEDs were also of low intensity, and limited to red. Modern LEDs are available across the visible, ultraviolet, and infrared wavelengths, with very high brightness.
- Infrared LEDs are still frequently used as transmitting elements in remote-control circuits, such as those in remote controls for a wide variety of consumer electronics.
- LEDs have many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching.
- Light-emitting diodes are now used in applications as diverse as aviation lighting, automotive headlamps, advertising, general lighting, traffic signals, camera flashes and lighted wallpaper.
Engineering ideas
- silicon, diode, semiconductor, intensity, infrared, visible, brightness, intensity, transmit, remote-control
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