Fluorescent lamps

Fluorescent Lamps

Fluorescent lamps are a type of gas-discharge light source that uses electricity to excite mercury vapor. The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow, producing visible light. Fluorescent lamps are more energy-efficient than incandescent lamps and have a longer lifespan.

History

The development of fluorescent lamps began in the early 20th century. Peter Cooper Hewitt invented the mercury-vapor lamp in 1901, which was a precursor to the fluorescent lamp. The first practical fluorescent lamp was developed in the 1930s by General Electric and introduced to the market in 1938.

Operation

Fluorescent lamps operate by passing an electric current through a gas, which in turn excites the mercury vapor. The basic components of a fluorescent lamp include:

• **Glass Tube**: The tube is filled with a low-pressure mercury vapor and an inert gas, usually argon.
• **Electrodes**: Located at each end of the tube, they emit electrons when heated.
• **Phosphor Coating**: The inside of the tube is coated with phosphor, which converts ultraviolet light into visible light.
• **Ballast**: A device that regulates the current through the lamp.

Starting the Lamp

When the lamp is turned on, the ballast provides a high voltage to the electrodes, which emit electrons. These electrons collide with mercury atoms, exciting them and causing them to emit ultraviolet light. The ultraviolet light strikes the phosphor coating, which fluoresces and emits visible light.

Types of Fluorescent Lamps

There are several types of fluorescent lamps, including:

• **Linear Fluorescent Lamps**: These are the most common type, typically used in office and industrial settings.
• **Compact Fluorescent Lamps (CFLs)**: Designed to replace incandescent bulbs, CFLs are smaller and more energy-efficient.
• **Cold Cathode Fluorescent Lamps (CCFLs)**: Used in applications such as backlighting for LCD screens.

Advantages and Disadvantages

Advantages

• **Energy Efficiency**: Fluorescent lamps use less energy compared to incandescent lamps.
• **Long Lifespan**: They last longer than incandescent bulbs.
• **Lower Heat Emission**: Fluorescent lamps emit less heat, making them safer and more efficient.

Disadvantages

• **Mercury Content**: Fluorescent lamps contain mercury, which is hazardous to the environment if not disposed of properly.
• **Flickering**: Some fluorescent lamps may flicker, which can be bothersome to some users.
• **Color Rendering**: The color rendering index (CRI) of fluorescent lamps is generally lower than that of incandescent lamps.

Environmental Impact

The presence of mercury in fluorescent lamps poses environmental challenges. Proper disposal and recycling are essential to prevent mercury from entering the environment. Many regions have regulations in place for the disposal of fluorescent lamps.

See Also

• Incandescent light bulb
• LED lamp
• Gas-discharge lamp

References

• "Fluorescent Lamp." Encyclopædia Britannica. Retrieved from [1]
• "How Fluorescent Lamps Work." HowStuffWorks. Retrieved from [2]