When it does, the electric power produces a temporary arc, sometimes an audible pop, and the bulb dies. Over time the glass darkens and the filament grows thinner-until at last it breaks. In vacuum bulbs these particles deposit on the glass, at its thick end if it is screwed in upside down, at its neck if it is installed in an upright position. Tiny portions of the super-heated filament boil away at high temperature while the bulb is on.

Vacuum bulbs are used for lower wattage lamps (40 watts and under) higher wattage bulbs are filled with gas. In the production process, the manufacturer draws all the air out of the bulb or replaces it with an inert gas. To put that much wire into a small bulb, it has to be coiled tightly and the coils coiled in turn.

In a 60 watt bulb the filament, if unwound, would be more than six feet in length. The longer the filament the more power the lamp can produce the higher the melting point, the more light the filament will emit. Tungsten is thus an ideal filament as it can be formed into a very thin wire and heated to a very high temperature while keeping its shape. Tungsten has the highest melting point of all elemental metals (6,192° Fahrenheit) and the second highest melting point of all elements only carbon has a higher melting point. A small portion of the electrical force, maximally 10 percent, turns into light the rest is released as heat. This resistance produces a very high temperature-approximately 4,600° Fahrenheit and higher. Tungsten does not conduct electricity well. Current enters the filament at one end and leaves at the other through a wire. The filament is mounted as a connector between the two poles of an electric circuit.

Incandescent lighting is produced by a filament made of tungsten, a metal. The category is also known as solid state lighting. The three major product groupings are incandescent lighting, represented by the ordinary household light bulb, plasma lighting, represented by fluorescent lights, and LEDs (light-emitting diodes), semiconductor light sources still in development. Modern lighting systems are classified by the device that converts electric power into light, thus by the technology behind the bulb or the tube. SIC: 3641 Electric Lamps, 3645 Residential Lighting Fixtures, 3646 Commercial Lighting Fixtures, 3648 Lighting Equipment, not elsewhere classified NAICS: 33-5110 Electric Lamp Bulb and Parts Manufacturing, 33-5121 Residential Electric Lighting Fixture Manufacturing, 33-5122 Nonresidential Electric Lighting Fixture Manufacturing, 33-5129 Lighting Equipment Manufacturing, not elsewhere classified

Illuminate mpcsd