Question

how led bulbs and tv are constructed?

Answer 1

Light-emitting diodes (LEDs)—small colored lights available in any electronics store—are ubiquitous in modern society. They are the indicator lights on our stereos,automobiledashboards, and microwave ovens. Numeric displays on clock radios, digitalwatches,and calculators are composed of bars of LEDs. LEDsalso find applications in telecommunications forshort range optical signal transmission such as TV remote controls. They have even found their way into jewelry and clothing—witness sun visors with a series of blinking colored lights adorning the brim. The inventors of the LED had no idea of the revolutionary item they were creating. They were trying to make lasers, but onthe way they discovered a substitute for thelightbulb.Light bulbs are really just wires attached to a source of energy. They emit light because the wire heats up and gives off some of its heat energy in the form of light. An LED, on the other hand, emits light by electronic excitation rather than heat generation. Diodes are electrical valves that allow electrical current to flow in onlyone direction, just as a one-way valve might in a water pipe. When the valve is "on," electrons move from a region of high electronic density to a region of low electronic density. This movement of electrons is accompanied by the emission of light. The more electrons that get passed across the boundary between layers, known as a junction, the brighter the light. This phenomenon, known aselectroluminescence,was observed as early as 1907. Before working LEDs could be made, however, cleaner and moreefficient materials had to be developed.