Light bulb

A light bulb or lightbulb, also known as an incandescent lamp, is a sealed body of glass (a bulb or globe) encasing a source of illumination. The globe contains two electrical points of contact, a filament (a coil made of tungsten that glows brightly when current is applied), and an amount of an inert gas.

The electric light bulb is usually credited to Thomas Alva Edison, who filed for a patent dated January 27, 1880 (patent #223898(US)); however multiple inventors and scientists at the time were also working to produce an incandescent bulb. Englishman Sir Joseph Swan produced an electric bulb in 1878.

In 1880 Edison and his engineering staff produced a bulb very similar to the one we have today, using a bamboo fiber filament lamp that lasted between 1200-1500 hours and was rated at 16 watts.

Modern light bulbs
Different types of light bulbs exist today as a result of lighting requirements and energy demands.


 * Compact Fluorescent Lights (CFLs) are smaller versions of fluorescent lights that are designed to fit into regular lamp sockets. The advantage of CFLs are that they produce mostly visible light but with very little power consumption.  However, CFLs contain mercury, a toxic heavy metal, so they should be recycled and not added to landfills.
 * LEDs, or Light Emitting Diodes, are small, compact sources of light usually integrated into electronics, although they have become more popular in consumer lighting because of the relatively low production cost, low energy demands, and high light output.
 * Halogen light bulbs were invented earlier than CFLs, and are a substitute for regular lighting applications, but the primary disadvantages are that the heat produced by a halogen bulb is much greater than that of an incandescent and has been the cause of some fires as a result. Halogen systems also require a special type of socket.  Some halogen systems may require an integrated step-down transformer which doesn't necessarily decrease the amount of power consumed, but allows for adjustment to be made from a "dimmer system" in order to control the amount of light produced by each bulb.