general picture of Light emitting diode
As the name suggest light emitting diode is a special types of diode that emits different wavelength of light . Different wavelength means different color .In the todays world LED are every where from a simple signal indicator to a LED display .Without a LED its just impossible to imagine todays colorful world .
What are Light Emitting Diode actually ?
As I said light-emitting diode (LED) is a semiconductor device that emits light on certain wavelength (color) when certain current flows through its terminal .It is a p–n junction diode, which emits light when activated. When a suitable voltage is applied to the leads, electrons are able to recombine with electron 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.
How does LED works ?
LEDs are made by using two type of semiconductor P-type and N-type .When electron are passed through it some electron from N-type material is recombine with P-type material emitting radiation of certain wavelength of photons and these photon cause light . For different color of LED the PN junction is made such a way that they produce specific wavelength . As shown in chart below for different color there are different wavelength . And if we combine Red , Green , and Blue (RGB) produce a white light .