About Glass Bulbs
The Light Bulb Today's incandescent light bulbs greatly resemble Edison's original lamps. The major differences are the use of tungsten filaments, various gases for higher efficiency and increased lumination resulting from filaments heated to higher temperatures. Although the incandescent lamp was the first and certainly the least expensive type of light bulb, there are a host of other light bulbs that serve myriad uses: Tungsten halogen lamps Fluorescent lamps are glass tubes that contain mercury vapor and argon gas. When electricity flows through the tube, it causes the vaporized mercury to give off ultraviolet energy. This energy then strikes phosphors that coat the inside of the lamp, giving off visible light. Mercury vapor lamps have two bulbs—the arc tube (made of quartz) is inside a protecting glass bulb. The arc tube contains mercury vapor at a higher pressure than that of the fluorescent lamp, thus allowing the v...