Many people are aware of the tube-like structure of neon signs and the white radiance of fluorescent lights. The two lights have much in common, and in many ways the fluorescent light can be seen as a descendant of the older neon light. Fluorescent lights are cheaper and have a much wider range of applications, but neon lights are still simple devices that have proved highly dependable over the years.
Neon lights are simple transparent tubes filled with a very high-pressure gas. This gas is a mixture of various elements, often argon and other noble gases, but most notably neon. These gases are neutral or even negative in nature, so they are not volatile when charged by an electrical current. However, the electricity does create energy in the atoms of the gas. This energy is released by the gas as visible light, which passes through the tubing.
Fluorescent lights are similar to neon devices. Like neon lights, a very carefully controlled electrical current enters the light and arcs from one end of the bulb to the other, passing through a gas on its way. However, the gas used in fluorescent lights has no neon. Instead, it uses a combination of argon and a small amount of mercury to create energy.
The gas in neon lights produces visible light that can be seen as long as the tube it fills is clear. However, the light produced by the fluorescent gas is actually ultraviolet light, beyond human sight. Fluorescent lights use a phosphor coating on their bulbs that absorbs the harmful ultraviolet radiation, and produces visible light in the characteristic fluorescent glow. This means that neon lights use only one step to produce light, while fluorescent lights use two steps.
Neon lights change color based entirely on what gases are used in the tube. Argon, xenon, krypton and other types of gas are used in varying amounts to produce different colors. This allows neon lights to radiate bright reds, blues, greens and other colors. Fluorescent lights, on the other hand, can produce light only in a range of whites that can tend toward red or blue, limiting their use in signs or displays.
Neon lights use a significant amount of voltage to start their gas reaction but only a small amperage, creating a soft glow that is not used to produce overhead lighting, only atmospheric or ambient light. Fluorescent lights use a much greater amount of electrical current, but in return they produce much brighter light that can be used for many applications.