The standard incandescent light bulb has not changed much since its invention over a hundred years ago. They work by exciting atoms to release photons, but most of the radiation is emitted as heat. Modern bulbs contain inert gases and a tungsten filament, which weakens over time. Fluorescent lights are more efficient, but can be difficult for some people and potentially trigger seizures in epileptics.
Standard incandescent light bulbs function today in essentially the same way they did when they were invented over a hundred years ago. Thomas Edison is generally credited with inventing the light bulb in 1879, although Sir Joseph Swan of England came up with the idea in 1878. Many inventors of the time were attempting to create a light source to replace the candles and oil lamps that they were not only dangerous, but dirty. By the turn of the century, millions of households had replaced fire and oil with the humble electric bulb.
At the most basic level, light bulbs work by exciting atoms which release photons of light. However, not all photons emit visible light. In fact, most of the radiation is emitted as heat rather than visible light. For this reason, light bulbs are not very efficient light generators by today’s standards.
The modern light bulb is a thin glass chamber filled with inert gases, usually argon. Two metal rods extend up into the chamber from the contacts at the base of the bulb. A tungsten filament connects the rods. Tungsten is a key element in light bulbs because it has a very high melting point. When electricity is applied to the bulb, it passes through the contacts, rods and connecting filament, exciting atoms in the tungsten which generate photons.
The excited atoms vibrate. Over time, the tungsten filament weakens as individual atoms vibrate free from the filament. This is one area where an improvement has been made in the way light bulbs work. The bulbs did not originally contain inert gases, but a vacuum which did nothing to keep the filament from losing atoms. The inert gases help extend the life of the filament by providing “bumper” atoms to help push back the atoms in the filament as they fly out. The way the bulbs work is now slightly more efficient than the original vacuum design.
Fluorescent lights have a different design that is more efficient than the way light bulbs work. The electricity charges the mercury vapor inside the tubular bulb, which in turn excites the phosphorus atoms to emit white light. Fluorescent lights are cooler, use less energy, and last longer than incandescent bulbs. However, some people find fluorescent lighting difficult. Flickering fluorescent lighting can also potentially trigger seizures in epileptics.
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