The cost of LED lighting is still high compared to an incandescent or arc-discharge lamp used for the same purpose, but the cost is decreasing rapidly.
42.
The term is now used for gas discharge lamps, which produce light by an arc between metal electrodes through an inert gas in a glass bulb.
43.
Hysteresis is due to the bulb's negative resistance, the fall in voltage with increasing current after breakdown, which is a property of all gas discharge lamps.
44.
The optics include of a 2.25m diameter lens, equipped with a 150 watt discharge lamp, which is connected to mains electricity and a back-up battery system.
45.
For the far-IR, especially at wavelengths beyond 50 �m ( 200 cm " 1 ) a mercury discharge lamp gives higher output than a thermal source.
46.
For example, the emission spectrum of a gas-discharge lamp can be altered by filling it with ( mixtures of ) gases with different electronic energy level configurations.
47.
Plasma " arc " or discharge lamps using hydrogen are notable for their high output in the ultraviolet, with comparatively little output in the visible and infrared.
48.
Typically, the sample was held in a long tube and illuminated along its length with a beam of filtered monochromatic light generated by a gas discharge lamp.
49.
Halogen lamps are more energy efficient than regular incandescent lamps but still fall far behind other more-recent types such as fluorescent lamps, gas discharge lamps, and LEDs.
50.
The warm-up time of the sulfur lamp is notably shorter than for other gas discharge lamps, with the exception of fluorescent lamps, even at low ambient temperatures.
