Image by cstmweb via Flickr
Author: Rodney Munch
Although simple devices, Light Bulbs are made up from many different parts, all working together to allow the bulb to safely emit bright light for an extended period of time.
The glass bulb, the largest and most noticeable part of the light bulb is generally made from a soft glass, although hard glass is sometimes used in light bulbs that emit higher temperatures to protect against breakage of the glass due to moisture. The glass is generally clear and colourless, although you can get them in many different colours depending on the application and they are available with a frosty coating to give off a softer light.
The glass bulb is filled with an inert gas such as argon or nitrogen. This is essential. If oxygen was left in the bulb, the filament would burn out very quickly and the bulb would have a very short lifespan. With an inert gas, combustion is prevented from occurring.
The filament in a light bulb is the part of the bulb which actually emits the light. This is a very fine piece of tungsten wire coiled up around itself many times. In a typical light bulb, stretched out, the tungsten filament is over 6ft long. Tungsten is used as it is very resistant to heat at temperatures where other metals would melt.
‘Lead in’ wires are the wires which carry the electrical current to the filament. They are generally made from nickel plated copper or nickel.
‘Tie wires’ are molybdenum wires which support the lead in wires.
Also visible within a light bulb but which serve no purpose after manufacture are the exhaust tubes. The exhaust tubes are the means by which oxygen is removed from the bulb and replaced with inert gas (see above). These tubes are subsequently sealed.
The base of the light bulb is where the electrical contact is made. This is the part which screws or locks into your light fitting depending on if it is a screw or bayonet fitting. Bases are most commonly made from aluminium or brass.
Higher wattage bulbs will sometimes have a heat deflector. The purpose of the heat deflector is to reduce the circulation of the hot gasses in the bulb, keeping it cooler.
Lastly, light bulbs have a fuse. The purpose of the fuse is the same as that of a fuse in any other electrical item and that is to protect the lamp and the circuit by blowing if the filament arcs.
As you can see, these seemingly simple and cheap to buy objects require quite a few parts to make them so get out there and light up a room. Not a cigarette or your neighbours house.
About the Author:
You can order light bulbs online from First Light Direct for great prices and fast delivery.
Author: Andy Quayle
Andy was born in the Isle of Man and currently lives in Pittsburgh.
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