Halogen vs. Incandescent

• Halogen and incandescent bulbs both are contain a filament coated in a chemical called tungsten, but halogen bulbs burn differently than incandescent bulbs do. When an incandescent bulb burns, it heats the filament, and tungsten evaporates into gas and is deposited onto the glass of the bulb. This is why some incandescent bulbs are clear when you install them but have a milky coating when you remove them.
  
  A traditional bulb burns out when so much tungsten has evaporated from the filament that there is no longer enough to create light.
  
  A halogen bulb, on the other hand, uses halogen gas to conduct evaporated particles of tungsten back to the filament after they have burned off. This prevents the tungsten from sticking to the walls of the light bulb, which can often create a brighter glow since it doesn't cloud the glass. Similarly, because tungsten flows back to the filament, it will not wear out as quickly, and the bulb will burn longer.
  
  Because of this conduction cycle, halogen bulbs can be 10 percent to 20 percent more efficient than incandescent lighting is and can burn two to three times longer.
  
  

Bulb Varieties

• A variety of halogen bulbs are available, and the kind you choose will depend on your specific lighting needs.
  
  MB halogen bulbs are the type you are most likely to buy if you are looking to replace the incandescent lighting in your home. These bulbs come in a variety of wattages, just like incandescent bulbs do, and you can screw them in to any light bulb socket used by incandescent lighting.
  
  Bigpin halogen bulbs are exactly what they sound like: small halogen light bulbs attached to long, large plug-in pins. These bulbs vary by wattage, voltage and space between the pins and often are used in areas with limited space, such as desk lighting, night lights or inside appliances.
  
  AR, H1 and H3 halogen bulbs are designed for more specialized use. For example, AR models provide a tight beam of light and so are often used for theatrical lighting (spotlights or shone directly onto artistic sculptures). H1 and H3 bulbs do not plug in or screw into light sockets, but instead come with electrical leads, making them ideal for science projects.
  
  Halogen bulbs are also used as flood lights for driveways and yards, colored lights for decoration and ball lights for light posts. All of these designs come with a variety of wattages or voltages, so find out what your light system will support before purchasing and installing.