What is a halogen used for in a halogen lamp?

Answer 1

Halogen light bulbs are used because:

• they can be operated at a higher temperature than can be used for ordinary light bulbs.

  This results in less heat production compared to light output and an overall much higher efficiency in the conversion of the energy which is input - electrical energy - to the energy which is output as visible light.

  and

• they have a significantly longer useful life than ordinary incandescent light bulbs.

Technical note

The invention of halogen lamps was based on the discovery of a special physical feature: when small amounts of a halogen gas were added to the contents of the light bulb, these were found to help to return large quantities of evaporated tungsten atoms back to the filament. This resulted in a significantly longer lifetime of such lamps.

General note about how all incandescent filament light bulbs operate

An electrical current travelling through the filament of a light bulb makes it glow white-hot and generate both light and heat because of the electrical resistance of the filament.

The filament is normally mounted within a special mixture of noble and/or inert gases held inside the glass enclosure of the light bulb, held at a pressure which is close to a vacuum.

The special mixture of gases prevents the filament from oxidizing and burning away, which would happen extremely quickly if it glowed white-hot in normal air which contains oxygen.

Answer 2

Halogen is introduced to increase the efficacy of the luminaire. It is called the halogen regenerative cycle because it removes carbon from the filament cycles it to the outer edge of the envelop where it cools then returns and deposits it on the filament

Answer 3

Incandescent lightbulbs operate by heating a tungsten (carbon originally) filament to incandescence. At these temperatures, some tungsten is 'cooked off' the filament and some of this tungsten is deposited on the glass envelope of the bulb causing it to darken as it is used. Halogen bulbs have a halogen gas in the bulb which 'encourages' the vapourised tungsten to redeposit on the filament which keeps the bulb's envelope clear which allows more light to pass through. Since the filament is not continually losing tungsten, it lasts longer.

Answer 4

Because the halogen cycle allows them to run at a higher temperature.

Answer 5

it gives of light to let people see