SOURCES OF LIGHT
When light sources are searched detailed, it is obvious that there are tens of light sources. If sources of the light classified, it should be classified like this:
- Direct Chemical
- Electric powered
First class of sources of light is “Natural”. Natural light sources are classed as Celestial and Atmospheric light source and the second one is Terrestial. For Celestial and Atmospheric light source the basic example is the Sun.The Sun light which is a type of solar radiation is the first and the main light source because at the creation of the space and planets, the first planet formed and lighted all other planets on the space is Sun. There are also Starlight or star clusters , moon light, galaxies, supernova…etc which are natural light sources too. On the other hand, there is Terrestrial Lighting sources. Here are some examples of Terrestrial LS; Bioluminescence,Volcanics, Lava, Earthquake light and some underwater creatures also some bugs.
Beside Natural light sources there is second type of light sources which are called “Direct Chemical”. Chemoluminescence are one of an example for direct chemicals which is a result of a chemical reaction. It can be explained as reactants A and B combine and after the natural chemical reaction it produces products and light. Fluorescence is also another subclass of direct chemicals. It is emission of light by the substance that has absorbed light or other electromagnetic radiation of a different wavelength. This absorption can lead to emission of radiation.
Thirdly, there are Combustion-based light sources which are usually lamps and inside the lamps there are some type of materials which are easy to combustion like oil or gas. Before the lamps inventioned, there are natural fire or torches and candles used from man-kind for thousands of years to get warm or light up their caves, houses, gardens or their ways during their journey. Then lamps discovered and humans started to use it in daily life. Now, lamps become common everywhere. For instance, oil lamps, gas lamps, butter lamp, argan lamp and betty lamp are examples of lamp type combustion-based source of light.
Fourth and the most common used type of light sources is Electric Powered light source. Basic concept of Electric Powered light sources depend on when electricity passed away from the circuit light, bulb or else lighted. Light bulb is simple example for electric powered light source. Basically, it lights out with the help of heating a metal filament wire to a high temperature until it glows. Filament is protected from air by thin layer glass. Next chapter, bulb and types of lights will be detailed explained. Therefore, for Electric Powerd light source it should be informed that there are bulbs, electron stimulated light source, incandescent lamps, electroluminescent lamps, gas discharge lamps and high-intensity discharge lamps used for Electric Powered light sources.