1.8.3 Gas-discharge lamps. The high-intensity discharge lamps use an arc array to produce light. The basic principle of a gaseous discharge lamp is illustrated in Fig. The filaments light up and instantly warm up the tube. Description. Gases are normally poor conductors, especially at atmospheric and higher pressures, but application of suitable voltage, called the ignition voltage, across the two electrodes can result in a discharge through the gas, which is accompanied by electromagnetic radiation. 7.32. Asim Kumar Roy Choudhury, in Principles of Colour and Appearance Measurement, 2014. The French astronomer Jean Picard observed (1675) a faint glow in a mercury-barometer tube when it was agitated, but the cause of the glow (static electricity) was not then understood. When the electrodes establish a potential difference, the gas gets ionized. Discharge tubes were made as early as 1856, but commercially discharge lamps came into the market only in the 1930s. A gas discharge lamp consists of a transparent gas discharge enclosure containing a small quantity of gas or vapour at a low pressure and two electrodes provided for connecting the lamp to the supply mains. Topics. Their applications extend across a range of domestic and commercial areas, and are affected by the type of gas being used. Energy Levels. When an AC voltage is applied to a tube light fixture, the voltage passes through the choke, the starter, and the filaments of the tube. Gas-discharge lamps are a family of artificial light sources that emit light by sending an electrical discharge through an ionised gas, i.e. The working principle of the Light-emitting diode is based on the quantum theory. As the filament continues to burn, particles fly off the filament. See how the characteristic spectra of different elements are produced, and configure your own element's energy states to produce light of different colors. Electric discharge lamp, also called Vapour Lamp, lighting device consisting of a transparent container within which a gas is energized by an applied voltage and thereby made to glow. Sample Learning Goals. Discharge lamps can be highly effective at maintaining luminosity for an extended period of time. The light in an incandescent light bulb is really just that effect occurring in a contained, controlled environment. Light. The quantum theory says that when the electron comes down from the higher energy level to the lower energy level then, the energy emits from the photon. Working Principle of UV lamps. The photon energy is equal to … Examples are metal halide lamps, sodium lamps, and sodium mercury lamps. The starter is made up of a discharge bulb with two electrodes next to it. High-intensity Discharge. Produce light by bombarding atoms with electrons. In high-pressure discharge lamps working pressure is greater than the atmospheric pressue. Formation of • UV lamp Main Operating Principles Electric current through the electrodes pass through the metal vapor discharge lamp. The halogen lamp has an instant 'on' ability unlike mercury vapor or high pressure sodium, therefore they work well for security lamps that are activated by motion sensors. Electrons. plasma. Cathodes, electrons (negative charge) or gas metal atoms colliding electrons spread rise higher energy level. The most common halogen lamps are double ended, these generally are the larger wattage lamps and are used for work lights, yard lights and film production lamps. High-Pressure Discharge. And when there are no more particles to burn, the light bulb burns out, which typically takes place 800-1,200 hours into the life of the incandescent light bulb. The ballast work on the principle of the inductor. This principle of the choke is exploited in lighting a fluorescent tube light. Lamp - Lamp - Electric discharge lamps: During the late 19th century, Sir William Crookes and other physicists experimented with methods of generating radiation by striking an arc between electrodes in an evacuated tube to which small amounts of an elemental gas had been admitted.