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How Does a Halogen Light Bulb Work?

We take a look at the science behind why halogen headlight bulbs work so effectively, and what made them leaps & bounds better than tungsten filament bulbs they replaced.

Unlike LED lights and HID (High Intensity Discharge), or Xenon lights, halogen light bulbs are not a "new" technology, but rather a refinement of an existing technology. Halogen bulbs are a variant of the traditional incandescent bulbs that have been used since the early days of the electric light.

Incandescent Light Bulbs

Halogen Bulb Types

A basic incandescent bulb works by using electrical current to heat a filament inside a glass bulb until it glows. The bulb is either evacuated (has a vacuum) or filled with an inert gas to keep the filament from oxidizing. Early light bulbs like those developed by Thomas Edison used a carbon filament inside a vacuum, but those had a short lifespan and didn’t burn very brightly.

Tungsten Filament Bulbs

In 1906, incandescent bulbs took a big leap forward when researchers discovered a filament made out of tungsten would produce a brighter light and last much longer. This made them practical for use on automobiles, which began using electric bulbs shortly thereafter in place of acetylene lights. Tungsten filament bulbs quickly became the mainstay of automotive lighting for most of the 20th century.

Tungsten Filament Bulb

Early tungsten filament bulbs were not without challenges though. Primarily, tungsten filaments in a vacuum evaporated more quickly during operation – at a rate that increased with operating temperatures. So there was a constant trade-off between the amount of light produced and a bulb's longevity. And as the tungsten evaporated off the filament, it would condense on the inner surface of the bulb – darkening the glass and blocking light output.

As the years passed, it was found that using an inert gas like argon inside the bulb (instead of a vacuum) would reduce tungsten evaporation and prolong filament life. However, the argon gas also cooled the filament and reduced its efficiency – so these bulbs still weren’t perfect.

Halogen Bulbs

Light Bulb With Black Casing

Developed in the late 1950s, halogen bulbs used halogen elements such as iodine and bromine inside the bulb instead of inert gasses like conventional bulbs did. This was another big leap forward, because halogen gas and tungsten filaments combine to produce a chemical reaction called the “halogen cycle”. The main benefit of this was evaporated tungsten was re-deposited on the filament instead of blackening the glass part of the bulb. Filaments lasted a lot longer, and they stayed bright over time because the blackening effect didn’t occur.

For this halogen cycle reaction to take place, bulbs must operate at higher temperatures. Thus, halogen bulbs are made of fused quartz glass which has a very high melting point and much higher tensile strength. Also known as quartz-halogen lights, the higher temperatures these bulbs reach allows them to produce more light from the same amount of power.

The first halogen bulbs for automobiles were used in Europe in 1962, but did not become legal for use in the United States until 1978. Today, halogen bulbs are still commonly used for headlights and fog lights, and their increased light output increases driver visibility in darkness and inclement weather. Halogen bulbs are available in several degrees of brightness and color variation ranging from bright white to blue to yellow.

Halogen Bulbs We Offer

When you’re in need of replacement halogen headlight bulbs that match or exceed the output and quality of your OE ones, we’ve got you covered. For best value, check out EVO Lighting Vistas Headlight Replacement Bulbs. We’ve also got replacement halogen headlight bulbs from Putco, Philips, PIAA, Sylvania, AC Delco, and General Electric just to name a few. Depending on vehicle application, some of these might be available in more than one shade of light output.

Oracle Lighting Chrome Halogen Bulbs
Oracle Lighting Chrome Halogen Bulbs are designed to blend in with your headlamp assembly background.

And if you’d like to add a little style, we’ve got Oracle Lighting Chrome Halogen Bulbs which have a mirrored glass finish that allows them to blend in with the chrome reflector background inside the headlamp assembly.

Vehicle Selector Box
To quickly find any halogen headlight bulbs for your specific make and model, we recommend using the Vehicle Selector box found at the top of the screen.

Most of these are produced for a wide range of make and models, designed to fit as easily and securely as original equipment bulbs do. However, we also recommend using the vehicle selector box at the top of the screen. Once you enter specific vehicle info and hit the “go” button, you’ll see all applicable products that will fit your ride.

Headlight Bulbs Variety Gallery

Once you’ve got new headlight bulbs in place, you’ll be riding easy at night with safety under your wings. We welcome questions you have regarding any of the headlight bulbs we sell, so don’t hesitate to give us a call; we’re here seven days a week!

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