Electrical Engineering

HOW ELECTRIC LIGHT IS PRODUCED

If you could open an electric-light bulb, you would see two heavy metal wires sticking up from the base, with a very fine wire between their ends. This fine wire, which is called a "filament", is made of the metal tungsten.

Tungsten is a conductor of electricity, that is, its atoms allow electrons to escape so that there are free electrons in the tungsten wire. When the filament is connected to a generator, electrons try to push through the filament. The filament is hardly larger than a human hair, however, so that not very many electrons are able to get through easily. In spite of that, many electrons try to push through, because electric pressure, or voltage, is pushing them. As a result, the filament becomes crowded with electrons and electrons are constantly pushing the atoms of tungsten.

Soon the atoms are in violent movement. Fast atom­ic or molecular movement is heat. Thus, the tungsten filament becomes hot and begins to glow — to give off light.

The filament is enclosed in the glass bulb so as to keep oxygen in the air away from the filament. If oxygen were present, it would combine with the hot tungsten. In other words, the tungsten filament would burn out. The bulb keeps the air out and prevents this from happening.