A basic guide to light bulb technology
Author: Mark Chapman
Published: November 6, 2012
Ever since the invention of artificial lighting, in the dim and distant past, we’ve rather relied on it to separate us from the animals and allow our lives and work to not be governed by the rising and setting of the sun. And while you may curse this technological freedom every time you’re still sat at your desk come 8pm, you probably don’t think too much about where the light that allows you to see your keyboard is coming from.
Perhaps you should though, as how each type of light bulb or tube is powered has a great effect on how efficient it is, where and when it should be used (and for how long), and indeed where it can’t be used. Of course where the light came from was a whole lot easier to figure out back in the days of guttering torches on the walls, or gas-powered lanterns, but in this guide, we’ll get to the bottom of how more modern light sources work.
Starting at the beginning, the incandescent bulb is the oldest lighting technology still in widespread use, although as is widely known, it’s being slowly phased out. Incandescent bulbs work in a very simple way, by passing electricity through a metal filament until it glows brightly (technically the filament doesn’t even need to be a piece of metal – you can achieve the same result with a cucumber!). The purpose of the glass bulb is partly to protect users from electrocution, but it also contains inert gas or a vacuum, to protect the filament and increase its lifespan.
Incandescents are being replaced for most uses by new energy-saving and LED bulbs, which offer a far greater lifespan and are better for the environment, but they still have their uses in some applications. There is still a wider range of coloured bulbs available in incandescent, and certain specialised bulbs for fridges, cookers and the like aren’t yet available in other versions. Incandescent bulbs are also useful in spaces used by the minority of people who find themselves sensitive to fluorescents or energy-saving bulbs.
Speaking of incandescents, you may not realise that halogen bulbs are just another form of incandescent bulb. The difference being that it’s filled with halogen, which redeposits metal back onto the tungsten filament, allowing it to burn brighter, for longer. The main advantages of halogen bulbs are their intense brightness and tiny size, making them ideal for car headlights, recessed downlights and desk lamps as well as uses in the TV and film industry.
While these may be our oldest common lighting technology, fluorescent tubes are no spring chickens either. These work in a somewhat different way to incandescents, as they rely on a current passing through mercury vapour, causing them to release ultraviolet light that makes phosphor glow. The key advantage of fluorescent tubes is that they can be made in large sizes and can produce a large amount of light for relatively little energy cost, so they’re ideal for lighting large areas such as open-plan offices, warehouses, corridors and similar spaces. Fluorescents aren’t just available as straight tubes however – they also come as circular tubes, and due to the technology in them, are also available as UV tubes, should you happen to run a nightclub, bar or ghost train (or just want to have impressive-looking parties).
Sticks, Spirals & Low energy bulbs
Speaking of funny-shaped tubes, you might be thinking that energy-saving stick or spiral bulbs are a completely different technology than those big fluorescent tubes. Well, they’re not. An energy-saving bulb is just a fluorescent tube curled into a different shape. These are available as the aforementioned sticks and spirals, as well as covered bulbs that look more like traditional incandescents. Energy-saving bulbs, as the name suggests, use far less electricity than incandescents, and have a much longer lifespan, thus saving you money and protecting the environment. They also don’t give off anywhere near as much heat, meaning they’re ideal for temperature-controlled environments, and are less likely to heat damage fittings.
Finally, the latest form of home and business lighting technology to become popular is LED lighting. Thus LED lights take the form of either tiny individual lights, such as the power light on your television or laptop (or in the ‘fairy lights’ round the front of modern sports cars), or clusters of individual LEDS, which combine to give off a greater amount of light, such as in LED spotlights or bulbs. Still a fairly young technology, LED bulbs are improving all the time, and have started appearing in forms such as candle and golfball, as well as coloured and even colour-changing bulbs. As with energy-savers, LED bulbs offer a far extended lifespan and much reduced energy costs, and also have a smaller heat profile than incandescents.
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