Tungsten-filament light bulb

Real or gray bodies deviate from these ideal blackbody values by the A-dependent emissivity, but the color sequence remains essentially the same. This mechanism explains the color of incandescent light sources such as flames in a candle, tungsten filament light bulb, flash bulb, carbon arc, limelight, lightning in part, and the incandescent part of pyrotechnics (qv). 

The same properties that make molybdenum metal effective in high temperature furnace appHcations make it useful as support wires for tungsten filaments in incandescent light bulbs and as targets in x-ray tubes. 

It is widely used by the electronics industry in the manufacture of capacitors, where the oxide film is an efficient insulator, and as a filament or filament support. Indeed, it was for a while widely used to replace carbon as the filament in incandescent light bulbs but, by about 1911, was, itself superseded by tungsten. 

The term plastic is not a definitive one. Metals, for instance, are also permanently deformable and are therefore plastic. How else could roll aluminum be made into foil for kitchen use, or tungsten wire be drawn into a filament for an incandescent, light bulb, or a 100 ton ingot of steel be forged into a rotor for a generator. Likewise the different glasses, which contain compounds of metals and nonmetals, can be permanently shaped at high temperatures. These cousins to polymers and plastics are not considered plastics within the plastic industry or context of this book. 

Langmuir s research on how oxygen gas deteriorated the tungsten filaments of light bulbs led to a theory of adsorption that relates the surface concentration of a gas to its pressure above the surface (1915). This, together with Taylor s concept of active sites on the surface of a catalyst, enabled Hinshelwood in around 1927 to formulate the Langmuir-Hinshelwood kinetics that we still use today to describe catalytic reactions. Indeed, research in catalysis was synonymous with kinetic analysis... 

The lifetime of a tungsten filament in an incandescent light bulb depends a great deed on the grain size of the wire used to make the filament. W-metal powder is pressed into a bar at pressures which ensure that the density is as... 

Small amounts of thorium are used in alloys with tungsten to produce the spiral filaments of light bulbs. Higher temperature generate a brighter light. 

The dark spot on the inside of a burned-out light bulb is tungsten metal that has sublimed (vaporized from the solid) as a consequence of the heating of the tungsten filament to produce white light. 

The electrical uses of mercury include its application as a seal to exclude air when tungsten light bulb filaments are manufactured. Fluorescent light tubes and mercury arc lamps that are used for street lighting and as germicidal lamps also contain mercury. 

The filament in a light bulb is made of tungsten because its melting point is so high. Operation of the bulb near its maximum temperature enables the value of A.(maX) to shift to shorter wavelengths, i.e. closer to the sensitivity of the human eye. 

Unalloyed tungsten has several major applications. An important use is in the electric lamp filaments for light bulbs. Also, it is used as electrodes in arcwelding, in heating elements for high-temperature furnaces, in electron and television tubes, in glass-to- metal seals, and in solar energy devices. 

When an object is heated, it emits radiation—it glows. Even at room temperature, objects radiate at infrared frequencies. Imagine a hollow sphere whose inside surface is perfectly black. That is, the surface absorbs all radiation striking it. If the sphere is at constant temperature, it must emit as much radiation as it absorbs. If a small hole were made in the wall, we would observe that the escaping radiation has a continuous spectral distribution. The object is called a blackbody, and the radiation is called blackbody radiation. Emission from real objects such as the tungsten filament of a light bulb resembles that from an ideal blackbody. 

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