1. Inert Gas:
* Argon (Ar): This is the primary gas inside the tube. It's an inert gas, meaning it doesn't readily react with other substances, which is crucial for the lamp's operation.
* Neon (Ne): While less common, neon can sometimes be used as an alternative to argon.
2. Mercury Vapor:
* Mercury (Hg): This is the key element that produces the UV light within the tube. A small amount of liquid mercury is placed inside the tube, which vaporizes when the lamp is turned on.
3. Phosphor Coating:
* Phosphors: The inside of the tube is coated with a fluorescent powder called phosphor. This coating absorbs the invisible ultraviolet (UV) radiation emitted by the mercury vapor and re-emits it as visible light. Different phosphor compounds create different colors of light.
How it Works:
1. Electricity: When the lamp is switched on, electricity flows through the electrodes at the ends of the tube.
2. Ionization: The electric current ionizes the argon gas, creating a plasma.
3. Mercury Vapor: The ionized argon atoms collide with the mercury vapor, causing the mercury atoms to become excited and emit UV light.
4. Phosphor: The UV light strikes the phosphor coating, causing it to fluoresce and emit visible light.
Important Notes:
* Pressure: The pressure inside the tube is very low, typically less than 1% of atmospheric pressure.
* Color: The specific type of phosphor used determines the color temperature of the light emitted.
* Efficiency: Fluorescent lamps are much more energy-efficient than incandescent bulbs because they convert a larger percentage of electrical energy into light.
Safety:
* Mercury: Fluorescent lamps contain a small amount of mercury, which is a toxic substance. It's important to dispose of them properly to avoid environmental contamination.
* UV Radiation: While the phosphor coating absorbs most of the UV radiation, some may still be emitted. It's best to avoid looking directly at the tube when it's lit.
