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A light source made by people is called an artificial source. At first people burnt wax or oil and, later, gas, to produce light.
Today, electric light bulbs and fluorescent lights are mostly commonly used .Artificial light is essential to our way of life. There are two main types of artificial light sources. In one, solid or liquid material is heated. An electric light filament, heated by electricity, glows very brightly, producing a whitish light .The filament is a coil of thin metal, usually tungsten. The metal magnesium can burn in air, producing an almost blinding light. The colour of the light emitted by the material depends on its temperature. The hottest materials glow bluish-white. As their temperature drops, the glow becomes more yellow, then red and finally disappears .It is still very hot, however.
The inventor Thomas Alva Edison experimented with thousands of filaments to find just the right materials to glow well and be long-lasting .In 1879 , Thomas Edison discovered that a carbon filament in an oxygen free bulb , it glowed and did not burn up for 40 hours .Edison finally produced a bulb that could glow for over 1500 hours.