What are they?

The incandescent light bulb or lamp is a source of electric light that works by incandescence, which is the emission of light caused by heating the filament. They are made in an extremely wide range of sizes, wattages, and voltages.

Where did they come from?

Early Incandescent BulbIncandescent bulbs are the original form of electric lighting and have been in use for over 100 years. While Thomas Edison is widely considered to be the inventor of the incandescent bulb, there are a number of people who invented components and prototypes of the light bulb well before Edison did. One of those people was British physicist Joseph Wilson Swan, who actually received the first patent for a complete incandescent light bulb with a carbon filament in 1879. Swan’s house was the first in the world to be lit by a light bulb. Edison and Swan merged their companies and together they were the first to design a bulb that was commercially viable.

How do they work?

An incandescent bulb typically consists of a glass enclosure containing a tungsten filament. An electric current passes through the filament, heating it to a temperature that produces light. Incandescent light bulbs usually contain a stem or glass mount attached to the bulb's base which allows the electrical contacts to run through the envelope without gas/air leaks. Small wires embedded in the stem support the filament and/or its lead wires. The enclosing glass enclosure contains either a vacuum or an inert gas to preserve and protect the filament from evaporating.