Two of the most common plasma devices on the planet are the fluorescent light bulb, and its cousin, the neon sign. Since their development in the 1940 s, fluorescent bulbs have become the lighting fixture of choice in offices, factories, and schools, and they are beginning to be found more widely in homes as well.
Neon signs operate on similar principles, and are nearly as common.
This page will outline some of the physics behind these ubiquitous devices, focusing on the fluorescent light. We will begin with the light we can see from the outside of the bulb and work our way inward to see what makes them work. In the case of the fluorescent bulb, the material that is actually doing the glowing is a white powder applied to the inner wall of the bulb s long glass tube. In order to glow with its familiar white light, the phosphor needed to be bombarded with uv light from within the bulb. This uv was emitted by mercury atoms present in the partially-evacuated fluorescent tube.