An incandescent light bulb works by passing an electric current through a thin filament, heating it until it produces light. Incandescent bulbs are made in a wide range of sizes and voltages. Incandescent light bulbs are gradually being replaced by fluorescent lamps, LEDs and other newer technologies. The new technologies give more visible light for the same amount of energy and typically generate much less heat. As part of regulations in the European Union, incandescent light bulbs are being phased out in favour of more energy-efficient lighting.
Compact Fluorescent Lamp (CFL)
A compact fluorescent lamp (CFL) is a type of fluorescent lamp. Many CFLs are designed to replace an incandescent lamp and can fit into most existing light fixtures formerly used for incandescent light bulbs. CFLs generally use less power, have a longer rated life and give the same amount of light, but at a higher purchase price. Like all fluorescent lamps, CFLs contain mercury, which complicates their disposal. CFLs radiate a different light spectrum from that of incandescent lamps, but are becoming more similar in colour output to the standard incandescent light bulb.
A halogen lamp consists of a tungsten filament sealed in a compact transparent envelope filled with an inert gas and a small amount of halogen such as iodine or bromine. The halogen iodine or bromine increases the lifetime and the luminous efficiency of the lamp. Halogen lamps reach a luminous efficiency of approximately 25 lumens per watt (a conventional incandescent light bulb is approximately 15 lumens per watt and a compact fluorescent lamp is approximately 60 lumens per watt). Halogen bulbs are smaller than conventional light bulbs.
Metal halide lamps are a group gas-discharge lamps that contain halogens as the filling. They produce a great amount of light for their size. With very high luminous efficiencies and a good colour reproduction, metal halide is one of the most efficient lamps. They are used mainly for commercial applications (e.g. halls, stages, traffic and outdoor lights).
LED or Light-Emitting Diode
A light-emitting diode (LED) is an electronic light source. LEDs radiate light through the movement of electrons in a semiconductor material. LEDs last for an amazing amount of time, give off virtually no heat and contain no hazardous materials.
A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapour. Fluorescent lamps reach a luminous efficiency of approximately 45 to 100 lumens per watt (in comparison to the normal lamp approx. 10-15 lm/W) and thus have a high energy efficiency. Compared with incandescent lamps, fluorescent lamps use less power for the same amount of light, generally last longer, but are bulkier, more complex, and initially more expensive than a comparable incandescent lamp.
A neon lamp is a gas discharge lamp containing primarily neon gas at low pressure. The term is sometimes used for similar devices filled with other noble gases, usually to produce different colours. The application of a high voltage (usually a few thousand volts) makes the gas glow brightly.