How a Light Bulb Works

The structure of a lightbulb is very simple, considering the trouble it gave scientist for so many years, and really has not changed much at all from the basic structure of bulb with which they worked.

The structure begins with a glass bulb filled with an inert gas. At the bottom of this bulb are two metal electrical contacts each of which is connected to its own stiff metal wire. These metal wires extend into the glass bulb and are each connected to an end of a tungsten metal coiled filament that is supported within the bulb by a glass support that raises up through the center.

 

When an electric current is passed into the bulb the current flows from the negative contact, through the tungsten filament, to the positive contact. This electric current that moves through the solid metal conducting components of the bulb are simply the "mass movement" of free electrons from the negative charge to the positive charge.

As these free electron move through the filament at high speeds they are constantly bumping into the atoms that make up the filament, the impact energy vibrating and heating these atoms. Bounded electrons in the atoms of the filament are temporarily boosted to a higher energy level. When the electron returns to its original energy level they release the extra energy in the form of photons. Metal atoms release primarily infrared light photons which happen to be invisible to the human eye, but if heated to a high enough temperature (around 2,200 C) will emit the visible light seen from a bulb.