A RED light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting.
When a light-emitting diode is switched on, electrons are able to recombine with holes within the device, releasing energy in the form of photons. This effect is called electroluminescence and the color of the light (corresponding to the energy of the photon) is determined by the energy band gap of the semiconductor. An LED is often small in area (less than 1 mm2), and integrated optical components may be used to shape its radiation pattern. LEDs present many advantages over incandescent light sources including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. However, LEDs powerful enough for room lighting are relatively expensive and require more precise current and heat management than compact lamp sources of comparable output. LEDs require a lot less power to light up by comparison. They’re also more energy efficient, so they don’t tend to get hot like conventional lightbulbs do (unless you’re really pumping power into them). This makes them ideal for mobile devices and other low-power applications. Don’t count them out of the high-power game, though. High-intensity LEDs have found their way into accent lighting, spotlights and even automotive headlights!
This is a very basic 5mm LED with a red lens. It has a typical forward voltage of 2.0V and a rated forward current of 20mA., 1.8-2.2VDC forward drop, Max current: 20mA, Suggested using current: 16-18mA, Luminous Intensity: 150-200mcd