Incandescent lighting is the oldest and one of the most well known forms of electric illumination. The name is derived from the method used by incandescent lamps to generate light. This style of lighting is seen from thermal radiation from the heating of an object, whether it is the sun, a light bulb filament, or a candle wick.
Most people are familiar with incandescent lighting in the form of light bulbs that heat a tungsten filament inside a sealed glass globe. A current of electricity is sent into the bulb. This current transfers energy to the tungsten atoms which begin to heat. The tungsten filament then heats to 4,532°F (2,500°C). If there were any oxygen in the sealed bulb, the tungsten would catch on fire, so most incandescent lamps are filled with a mixture of nitrogen and an inert gas such as argon.
Incandescent lighting is the result of the thermal radiation that is emitted from the filament. About 12% of that radiation is visible light. This makes incandescent bulbs one of the least energy efficient choices, since the majority of the energy released is in the form of heat rather than light.
Incandescent lighting has been around since the birth of the sun, but the incandescent bulb has a much shorter history. Prior to the 19th century, lighting was the from the sun or candles, but by the mid-eighteen hundreds people began to experiment in creating an electric light bulb. Finally, within a year of each other, between 1878 and 1879, Sir Joseph Swan of Great Britain and Thomas Edison of the United States created light bulbs which used a filament inside to generate light. Swan's invention was first, but it is Edison who is remembered by history for the deed. Their designs for incandescent light bulbs were almost identical, and it is still the basis for incandescent lighting used today.
Other commonly encountered instances of incandescent lighting are candlelight and sunlight. These two forms of light appear different in coloring because the temperature of the object releasing thermal radiation is critical to their appearance. The color is a result of the wavelength of the light emitted, and the more energy used, the shorter the waves will be. In a light spectrum, red has the longest wavelength, and the least amount of energy while blue or violet has the shortest wavelength and most energy. Since the sun burns nearly two and a half times hotter than the tungsten filament in an incandescent light bulb, or the flame from a small candle, its light has more blue than red, and for this reason, appears to be whiter.
