How halogen lightbulbs work

Roots of the Halogen Light Bulb - Incandescents

Over 100 years ago, Thomas Edison invented the incandescent light bulb. Simple, elegant and cheap, it quickly became the standard way to turn electricity into light. In the design, a glass bulb encloses a small wire (called a filament) which glows when electricity is passed through it.

The filament is made of tungsten, a strong and resilient metal, which can take the high heat without falling apart. And it doesn't burn up because there is no oxygen inside the bulb.

The Catch with Incandescent Bulbs 

But even though the filament doesn't "burn", the extreme heat required for incandescence causes it to undergo a form of evaporation.

The filament gradually gets thinner and thinner, and the evaporated tungsten ends up on the glass as a visible dark spot.

After about 750 to 1000 hours of use, the filament gets so thin that it breaks, and this is why light bulbs "burn out".

The halogen bulb offered a new solution.

Halogen Light Bulbs PictureEnter Halogen

A halogen light bulb is also an incandescent design, with a few key differences.

It also uses a tungsten filament, but instead of a glass bulb, the filament is enshrouded in a smaller quartz "envelope".

Inside is a halogen gas which has a special property -- it is able to combine with tungsten vapor.

At a high enough temperature, the evaporating tungsten combines with the halogen gas, which redeposits the tungsten onto the filament again. So essentially, a halogen light bulb has its own recycling program.

This enables a halogen light bulb to last two to three times longer than a regular incandescent light bulb.

In addition, the quartz envelope can withstand much higher temperatures than glass, so a halogen light bulb can run hotter and therefore produce more light.

MR Halogen Light Bulb Picture

To recap, let's summarize the three key advantages of halogen light bulbs over standard incandescent light bulbs.

  • They last two to three times longer.
  • They are smaller in size.
  • They can get brighter.

These advantages make halogens the bulb of choice for a wide range of applications, from kitchen and bath lighting to reading lights and desk lamps.

Handling Halogen Bulbs

It's important to remember that you should never touch a halogen light bulb with your bare fingers. The oils on your fingers and skin can damage the quartz glass, creating a hot spot on the surface of the bulb when illuminated.

These hot spots can cause a weakening in the bulb glass, causing it to burn out or even explode.

Because of this, we always recommend that halogen bulbs never be handled by your bare hands. Use gloves or clean paper when holding the bulb so that you do not touch it with your bare skin.

Learn More

For more information on light bulb types, visit our Lamps Plus light bulb information page. 

Or read more about different kinds of bulbs:

1. How an LED Bulb Works

2. How an Incandescent Bulb Works

3. How a CFL Bulb Works

Need Help With Halogen Light Bulbs?

Need help finding a halogen light bulb or other light bulb that meets your needs? Our American Lighting Association trained consultants are here for you! Use our Lamps Plus store locator page to find a location near you, or contact us for more information.