The byproduct of the resistance is heat with the filament glowing ‘white-hot’ you create light, which is then reflected out of the spotlight. The light they generate is due to the filament glowing when electricity is passed through it, and the resistance of that filament. The halogen within the bulb assists in keeping the tungsten together and allows the bulb to burn brighter than a standard incandescent bulb, and last longer. Within the sealed bulb is an inert gas mixed with a touch of a halogen gas (usually iodine or bromide). Essentially, the bulbs are sealed (not to be confused with ‘sealed beam’ lights) and have a wire filament (usually made from tungsten) between two pins. Halogen bulbs have been around for a very long time they are the simplest of our lights. We’ll start with the grandad of the lot: Halogen incandescent bulbs. In this article, we’ll look at the different technology of the spotlights most prevalent on the market, and in a follow-up article in an issue or two, I’ll take the lights out into the night and run some testing on their light output, power usage, heat issues, and which works best in which situation. It’s the question that gets both Facebook experts and armchair engineers up in arms just about every day: Which is the best lighting technology for a spotlight? Interestingly enough, the question is a lot more subjective than you may realise, where understanding the technology and the way light is generated will allow you to choose the best lights for you.