Hello everyone! Now, we’re going to learn about a special type of incandescent lamp called the Tungsten Halogen Lamp, often abbreviated as TH lamp.

1. What is a Tungsten Halogen Lamp?

A tungsten halogen lamp is an improved version of the traditional tungsten filament lamp. It contains a small amount of halogen gas—usually iodine or bromine—inside the bulb.

2. How Does It Work?

Just like a regular tungsten lamp, an electric current heats the tungsten filament, making it glow and produce light.

But here’s the difference: The halogen gas reacts with the tungsten atoms that evaporate from the filament. Instead of settling on the glass and darkening the bulb, the halogen gas redeposits tungsten back onto the filament. This process is called the halogen cycle.

This recycling keeps the filament strong for a longer time and helps the lamp last longer and stay brighter.

3. Advantages of Tungsten Halogen Lamps

• Higher efficiency than traditional tungsten lamps — they produce more light per watt.

• Longer lifespan due to the halogen cycle.

• Produce bright, white light with good color rendering.

• Smaller size allows for compact lamp designs.

• Can operate at higher temperatures.

4. Disadvantages

• Operate at very high temperatures, which can be a safety concern.

• More expensive upfront than standard incandescent lamps.

• Require special handling because the glass can get extremely hot.

• Contain halogen gas, which requires careful disposal.

5. Common Uses

Tungsten halogen lamps are widely used in:

• Automotive headlights

• Stage and studio lighting

• Projectors

• Task lighting (like desk lamps)

• Some household and outdoor lighting fixtures

6. Quick Review Questions

Let me ask you a few quick questions to check your understanding:

• What gas is inside a tungsten halogen lamp?

• What is the main benefit of the halogen cycle?

• Why do tungsten halogen lamps last longer than regular incandescent lamps?

Closing

To sum up, tungsten halogen lamps are an advanced form of incandescent lamps with better efficiency and lifespan, thanks to the halogen cycle. However, they do require careful handling because they run very hot.

Next, we will explore even more energy-efficient lighting technologies like discharge lamps and LED lamps.