Incandescent lamps also known as electric light bulb, it is the working principle of electric current through the filament(tungsten wire, the melting point is more than 3000 degrees Celsius) to generate heat, spiral filament will gather heat continuously, the filament temperature above 2000 degrees Celsius, the filament in is in a state of incandescent, like burning red iron can shine, shine forth.
The higher the temperature of the filament, the brighter the light, so called incandescent lamp. Incandescent light, a lot of energy will be converted to heat energy, only a tiny part (probably less than 1%, has not calculated) can be converted into useful light.
All incandescent bulbs light is light, but all sorts of color composition ratio was determined by the luminous material (tungsten) and temperature. Ratio imbalance will lead to the color of light color, so the color of the object under incandescent lamp are not real enough.
Incandescent lamp life associated with the filament temperature, because the higher the temperature, the easier it is for the filament to sublimation.