Hello everyone! Now, we will explore another type of high-intensity discharge lamp — the Metal Halide Lamp. This type of lamp is known for producing very bright light and is used in large spaces like stadiums, factories, and commercial areas.

1. What is a Metal Halide Lamp?

A metal halide lamp is a type of HID (High-Intensity Discharge) lamp. It produces light by passing an electric arc through a mixture of gases, including mercury vapor and metal halide compounds inside a quartz or ceramic arc tube.

2. How Does It Work?

When the lamp is turned on:

• An electric arc forms between two electrodes inside the arc tube.

• The arc heats up the gases, including mercury and metal halides.

• The metal halide salts vaporize and release intense white light as the atoms get excited.

• A ballast is used to control the voltage and current.

Metal halide lamps need a warm-up period, usually 2–5 minutes, to reach full brightness.

3. Components of a Metal Halide Lamp

• Outer Bulb – protects the arc tube and provides UV shielding

• Arc Tube – contains the gases and electrodes

• Metal Halide Salts – improve efficiency and color rendering

• Ballast – regulates electrical flow

• Ignitor – helps start the arc

4. Advantages of Metal Halide Lamps

• High luminous efficiency (more lumens per watt)

• Bright, intense light suitable for large spaces

• Good color rendering index (CRI) — colors appear natural

• Longer lifespan compared to incandescent or halogen lamps (6,000–20,000 hours)

5. Disadvantages

• Longer warm-up and re-strike time

• Sensitive to position and temperature

• Contain mercury and require careful disposal

• Not as energy-efficient as LEDs

• Can degrade over time (color shift and reduced output)

6. Typical Applications

You can find metal halide lamps in places that require powerful and consistent lighting, such as:

• Sports stadiums and arenas

• Factories and warehouses

• Car parks and street lighting

• High-ceiling commercial areas

• Outdoor floodlights

7. Quick Review Questions

Let’s test your understanding with a few questions:

• What gases are used in a metal halide lamp?

• Why does it need a ballast?

• What makes metal halide lamps brighter than mercury vapor lamps?

Summary

To summarize, metal halide lamps are powerful light sources that produce bright, white light using a mixture of gases. While they offer excellent brightness and color rendering, they are gradually being replaced by more efficient and environmentally friendly technologies, like LEDs.