LED street light (Light Emitting Diode)

LED street light is vital for all creatures on earth, only the rare forms of life found in the ocean depths do not rely on light to survive. An important source of light is of course the sun, but during the night and in other dark conditions we have to rely on artificial lighting.
Historically, light has been produced the longest by different techniques based on burning. After the invention of electricity, the production methods for light have increased considerably and the efficiencies of light production have grown.
The incandescent lamp invented by Edison in 1879 is still the most common light production method in use. The light based on an incandescent filament was introduced much earlier in 1802 by Humphry Davy, who is better known for the arc lamp he introduced in 1810. Before Edison many others developed (22 people in total according to historians) and even patented the incandescent lamp, but Edison got it into a commercial shape due to his inventions of electricity production and distribution methods. For a long time, incandescent filaments made from coal was used in incandescent lamps, and the shift to the current tungsten filament took place in 1910.
It is thought that light emits particles known as photons or light quantum, which have no mass or charge. The modern quantum theory of light was introduced by Albert Einstein. In a vacuum, photons move at a speed of 300,000 kilometers per second. The word photon comes from the Greek φως meaning light.
The incandescent lamp’s operation is based on conducting electricity over the incandescent filaments acting as a resistor. The tungsten filament is inside an air-proof bulb in shielding gas, typically argon. Now when the electric current is conducted through the filament, the filament heats up powerfully to 2000 – 3300 Kelvin [K]. (On the Kelvin scale, the zero point is an absolute zero point –273,15 ºC.)
The heated filament radiates on a wide spectrum, of which only a small part is in the area of visible light. Most of this radiation is heat radiation and thus does not provide light, though the heat generated in houses with electric heating decreases the need for heating almost correspondingly. The incandescent lamps’ light efficiency is very small, only around 5%. The visible light’s amount unit is the SI standard’s unit lumen [lm].
The efficiency is thus calculated by dividing the amount of lumens produced by the power [W] used. The problem with incandescent lamps is also their relatively short life. Since the resistance of the incandescent light when cold is much smaller than when warm, the break usually happens when turning on the light, as the momentary big charge burns the incandescent lamp and cuts it.
The disadvantages of incandescent lamps have led to the development of new lighting techniques, among them the so-called energy saving light bulbs. These are partly problematic regarding the environment because of the mercury they contain. LED lighting has been developed as the newest lighting idea, which despite all the suspicions seems to become a very notable lighting method leading to energy savings.