What is a filament and what are the filament description codes?
A. A filament is a thin metal wire purposely positioned inside a lamp bulb, that generates radiation in the visible, infrared and ultraviolet ranges when electrical current is passed through it. Tungsten material is often used, as it has great tensile strength, is very durable, and can be heated very near its melting point without evaporating rapidly. Lamp filaments are offered in a variety of designs optimized for specific applications. A filament description consists of a prefix letter, to indicate whether the wire is straight or coiled, followed by a number to indicate the arrangement of the filament on the supports. Prefix letters are usually one of three options: • S – Straight, there is no coil to the filament • C – Coiled, the filament is wound into a helical coil • CC – Coiled Coiled, the helical coiled filament is wound again into another helical coil.
