A fluorescent lamp or fluorescent tube is a gas-discharge lamp that uses electricity to excite mercury vapor. Gas discharge lamps are a family of artificial light sources that generate light by sending an Electrical discharge through an ionized gas i Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum A vapor or vapour (see Spelling differences) is a substance in the Gas phase at a Temperature lower than its Critical temperature The excited mercury atoms produce short-wave ultraviolet light that then causes a phosphor to fluoresce, producing visible light. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays A phosphor is a substance that exhibits the phenomenon of Phosphorescence (sustained glowing after exposure to energized particles such as Electrons Fluorescence is a Luminescence that is mostly found as an Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700
Unlike incandescent lamps, fluorescent lamps always require a ballast to regulate the flow of power through the lamp. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric However, a fluorescent lamp converts electrical power into useful light more efficiently than an incandescent lamp; lower energy costs offsets the higher initial cost of the lamp. While larger fluorescent lamps have been mostly used in large commercial or institutional buildings, the compact fluorescent lamp is now being used as an energy-saving alternative to incandescent lamps in homes. Compared with incandescent lamps, fluorescent lamps use less power for the same amount of light, generally last longer, but are bulkier, more complex, and more expensive than a comparable incandescent lamp.
The history of the fluorescent lamp begins with early research into electrical phenomena. By the beginning of the 18th century, experimenters had observed a radiant glow emanating from partially evacuated glass vessels through which an electrical current passed. Little more could be done with this phenomenon until 1856 when a German glassblower named Heinrich Geissler (1815–1879) created a mercury vacuum pump that evacuated a glass tube to an extent not previously possible. Johann Heinrich Wilhelm Geißler ( May 26 1814 - January 24 1879) was a German Physicist and inventor of the Geissler tube This vacuum means "absence of matter" or "an empty area or space" for the cleaning appliance see Vacuum cleaner. When an electrical current passed through a Geissler tube, a strong green glow on the walls of the tube at the cathode end could be observed. The Geissler tube is a glass tube for demonstrating the principles of electrical Glow discharge.
Because it produced some beautiful light effects, the Geissler tube was a popular source of amusement. More important, however, was its contribution to scientific research. One of the first scientists to experiment with a Geissler tube was Julius Plücker (1801–1868) who systematically described in 1858 the luminescent effects that occurred in a Geissler tube. Julius Plücker ( June 16, 1801 &ndash May 22, 1868) was a German Mathematician and Physicist. He also made the important observation that the glow in the tube shifted position when in proximity to an electromagnetic field. Electromagnetism is the Physics of the Electromagnetic field: a field which exerts a Force on particles that possess the property of
Inquiries that began with the Geissler tube continued as even better vacuums were produced. The most famous was the evacuated tube used for scientific research by William Crookes (1832–1919). Sir William Crookes, OM, FRS (17 June 1832 – 4 April 1919 was an English Chemist and Physicist. That tube was evacuated by the highly effective mercury vacuum pump created by Hermann Sprengel (1834–1906). Hermann Sprengel (1834-1906 was a German Chemist. He discovered the explosive nature of Picric acid in 1873 and he invented a generic class of materials called Research conducted by Crookes and others ultimately led to the discovery of the electron in 1897 by J. J. Thomson (1856–1940). The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J Sir Joseph John “JJ” Thomson, OM, FRS (18 December 1856 &ndash 30 August 1940 was a British Physicist and Nobel laureate But the Crookes tube, as it came to be known, produced little light because the vacuum in it was too good and thus lacked the trace amounts of gas that are needed for electrically stimulated luminescence. A Crookes tube is an early experimental Discharge tube, invented by British physicist William Crookes and others around 1875 in which Cathode rays Luminescence is also the title of an album by singer Anggun. Luminescence is Light not generated by high temperatures alone
Alexandre Edmond Becquerel observed in 1859 that certain substances gave off light when they were placed in a Geissler tube. Alexandre-Edmond Becquerel ( March 24, 1820 - May 11, 1891) was a French Physicist who studied the Solar spectrum He went on to apply thin coatings of luminescent materials to the surfaces of these tubes. Fluorescence occurred, but the tubes were very inefficient and had a short operating life. A few years earlier another scientist, George G. Stokes (1819–1903), had noted that ultraviolet light caused fluorspar to fluoresce, a property that would become critically important for the development of fluorescent lights many decades later. Sir George Gabriel Stokes 1st Baronet FRS ( 13 August 1819 &ndash 1 February 1903) was a mathematician and physicist Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays Fluorite (also called fluorspar) is a Mineral composed of Calcium fluoride, Ca[[Fluorine F2]]
While Becquerel was primarily interested in conducting scientific research into fluorescence, Thomas Edison (1847–1931) briefly pursued fluorescent lighting for its commercial potential. He invented a fluorescent lamp in 1896 which used a coating of calcium tungstate as the fluorescing substance, but although it received a patent in 1907, it was not put into production. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 As with a few other attempts to use Geissler tubes for illumination, it had a short operating life, and given the success of the incandescent light, Edison had little reason to pursue an alternative means of electrical illumination. Nicola Tesla made similar experiments in the 1890's, devising high frequency powered fluorescent bulbs that gave a bright greenish light, but as with Edison's devices, no commercial success was achieved. There have already been discussions about Tesla's ethnicity on the talk page
Although Edison lost interest in fluorescent lighting, one of his former employees was able to create a gas-based lamp that achieved a measure of commercial success. In 1895 Daniel McFarlan Moore (1869–1933) demonstrated lamps 7 to 9 feet in length that used carbon dioxide or nitrogen to emit white or pink light, respectively. Daniel McFarlan Moore ( February 27, 1869 - June 15, 1936) was a U Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Nitrogen (ˈnaɪtɹəʤɪn is a Chemical element that has the symbol N and Atomic number 7 and Atomic weight 14 As with future fluorescent lamps, they were considerably more complicated than an incandescent bulb.
After years of work, Moore was able to extend the operating life of the lamps by inventing an electromagnetically controlled valve that maintained a constant gas pressure within the tube. Although Moore’s lamp was complicated, expensive to install, and required very high voltages, it was considerably more efficient than incandescent lamps, and it produced a more natural light than incandescents. From 1904 onwards Moore’s lighting system was installed in a number of stores and offices. Its success contributed to General Electric’s motivation to improve the incandescent lamp, especially its filament. GE’s efforts came to fruition with the invention of a tungsten-based filament. Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 The extended lifespan of incandescent bulbs negated one of the key advantages of Moore’s lamp, but GE purchased the relevant patents in 1912. These patents and the inventive efforts that supported them were to be of considerable value when the firm took up fluorescent lighting more than two decades later.
At about the same time that Moore was developing his lighting system, another American was creating a means of illumination that also can be seen as a precursor to the modern fluorescent lamp. This was the mercury vapor lamp, invented by Peter Cooper Hewitt (1861–1921) and patented in 1901 (U. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum A vapor or vapour (see Spelling differences) is a substance in the Gas phase at a Temperature lower than its Critical temperature Peter Cooper Hewitt ( May 5, 1861 - August 25, 1921) was an American electrical engineer who demonstrated the mercury-vapor lamp S. Pat. No. 889,692). Cooper-Hewitt’s lamp luminesced when an electric current was passed through mercury vapor at a low pressure. Unlike Moore’s lamps, those made by Cooper-Hewitt could be manufactured in standardized sizes and operated at low voltages. In Physics, the potential difference or pd between two points is the difference of the points' Scalar potential, equivalent to the line integral The mercury-vapor lamp was superior to the incandescent lamps of the time in terms of energy efficiency, but the blue-green light it produced limited its applications. It was, however, used for photography and some industrial processes.
Mercury vapor lamps continued to be developed at a slow pace, especially in Europe, and by the early 1930s they received limited use for large-scale illumination. Some of them employed fluorescent coatings, but these were primarily used for color correction and not for enhanced light output. Mercury vapor lamps also anticipated the fluorescent lamp in their incorporation of a ballast to maintain a constant current.
Cooper-Hewitt had not been the first to use mercury vapor for illumination, as earlier efforts had been mounted by Way, Rapieff, Arons, and Bastian and Salisbury. Of particular importance was the mercury vapor lamp invented by Küch in Germany. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. This lamp used quartz in place of glass to allow higher operating temperatures, and hence greater efficiency. Although its light output relative to electrical consumption was better than other sources of light, the light it produced was similar to that of the Cooper-Hewitt lamp in that it lacked the red portion of the spectrum, making it unsuitable for ordinary lighting.
The next step in gas-based lighting took advantage of the luminescent qualities of neon, an inert gas that had been discovered in 1898. Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 In 1909 Georges Claude (1870–1960), a French chemist, observed the red glow that was produced when running an electric current through a neon-filled tube. The French Engineer, Chemist, and Inventor Georges Claude ( September 24, 1870 &ndash May 23, 1960 He also discovered that argon emitted a a blue glow. This article pertains to the chemical element For other uses see Argon (disambiguation. While neon lighting was used around 1930 in France for general illumination, it was no more energy-efficient than conventional incandescent lighting. Neon lighting came to be used primarily for eye-catching signs and advertisements. Neon lighting was not irrelevant to the development of fluorescent lighting, however, as Claude’s improved electrode (patented in 1915) overcame “sputtering”, a major source of electrode degradation. Sputtering occurred when ionized particles struck an electrode and tore off bits of metal. Although Claude’s invention required electrodes with a lot of surface area, it showed that a major impediment to gas-based lighting could be overcome. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e
The development of the neon light also was significant for the last key element of the fluorescent lamp, its fluorescent coating. In 1926 Jacques Risler received a French patent for the application of fluorescent coatings to neon light tubes. The main use of these lamps, which can be considered the first commercially successful fluorescents, was for advertising, not general illumination. This, however, was not the first use of fluorescent coatings. As has been noted above, Edison used calcium tungstate for his unsuccessful lamp. Other efforts had been mounted, but all were plagued by low efficiency and various technical problems. Of particular importance was the invention in 1927 of a low-voltage “metal vapor lamp” by Friedrich Meyer, Hans-Joachim Spanner, and Edmund Germer, who were employees of a German firm in Berlin. Edmund Germer ( August 24, 1901 - August 10, 1987) was a German Inventor granted as the father of the Fluorescent lamp Berlin is the capital city and one of sixteen states of Germany. A German patent was granted but the lamp never went into commercial production.
All the major features of fluorescent lighting were in place at the end of the 1920s. Decades of invention and development had provided the key components of fluorescent lamps: economically manufactured glass tubing, inert gases for filling the tubes, electrical ballasts, long-lasting electrodes, mercury vapor as a source of luminescence, effective means of producing a reliable electrical discharge, and fluorescent coatings that could be energized by ultraviolet light. At this point, intensive development was more important than basic research.
In 1934, Arthur Compton, a renowned physicist and GE consultant, reported to the GE lamp department on successful experiments with fluorescent lighting at General Electric Co., Ltd. in Great Britain (unrelated to General Electric in the United States). Arthur Holly Compton (September 10 1892 &ndash March 15 1962 was an American physicist and Nobel laureate in physics for his discovery of the Compton effect The General Electric Company or GEC was a major UK company involved in consumer and defence electronics communications and engineering Stimulated by this report, and with all of the key elements available, a team led by George E. Inman built a prototype fluorescent lamp in 1934 at General Electric’s Nela Park (Ohio) engineering laboratory. Nela Park is the headquarters of GE Lighting, and is located in East Cleveland, Ohio, United States. This was not a trivial exercise; as noted by Arthur A. Bright, “A great deal of experimentation had to be done on lamp sizes and shapes, cathode construction, gas pressures of both argon and mercury vapor, colors of fluorescent powders, methods of attaching them to the inside of the tube, and other details of the lamp and its auxiliaries before the new device was ready for the public. ”
In addition to having engineers and technicians along with facilities for R&D work on fluorescents, General Electric controlled what it regarded as the key patents covering fluorescent lighting, including the patents originally issued to Cooper-Hewitt, Moore, and Küch. More important than these was a patent covering an electrode that did not disintegrate at the gas pressures that ultimately were employed in fluorescent lamps. An electrode is an Electrical conductor used to make contact with a nonmetallic part of a circuit (e This invention had been created by Albert W. Hull of GE’s Schenectady Research Laboratory, and was registered as U. S. Pat. No. 1,790,153.
While the Hull patent gave GE a basis for claiming legal rights over the fluorescent lamp, a few months after the lamp went into production the firm learned of a U. Law is a system of rules enforced through a set of Institutions used as an instrument to underpin civil obedience politics economics and society S. patent application had been filed in 1927 for the aforementioned "metal vapor lamp" invented in Germany by Meyer, Spanner, and Germer. The patent application indicated that the lamp had been created as a superior means of producing ultraviolet light, but the application also contained a few statements referring to fluorescent illumination. Efforts to obtain a U. S. patent had met with numerous delays, but were it to be granted, the patent might have caused serious difficulties for GE. At first, GE sought to block the issuance of a patent by claiming that priority should go to one of their employees, Leroy J. Buttolph, who according to their claim had invented a fluorescent lamp in 1919 and whose patent application was still pending. GE also had filed a patent application in 1936 in Inman’s name to cover the “improvements” wrought by his group. In 1939 GE decided that the claim of Meyer, Spanner, and Germer had some merit, and that in any event a long interference procedure was not in their best interest. They therefore dropped the Buttolph claim and paid $180,000 to acquire the Meyer, et al. application, which at that point was owned by a firm known as Electrons, Inc. The patent (U. S. Pat. No. 2,182,732) was duly awarded in December 1939. This patent, along with the Hull patent, put GE on what seemed to be firm legal ground, although it faced years of legal challenges from Sylvania Electric Products, Inc. , which claimed infringement on patents that it held.
Even though the patent issue would not be completely resolved for many years, General Electric’s strength in manufacturing and marketing gave it a pre-eminent position in the emerging fluorescent light market. Sales of "fluorescent lumiline lamps" commenced in 1938 when four different sizes of tubes were put on the market. During the following year GE and Westinghouse publicized the new lights through exhibitions at the New York World’s Fair and the Golden Gate Exposition in San Francisco. There have been two World's Fairs in New York City: 1939 New York World's Fair ( 1939 - 1940) at Fluorescent lighting systems diffused rapidly during World War II as industrial manufacture, stimulated by wartime needs, gave rise to intensified lighting demands. The use of fluorescent lighting continued to spread in the years following the war, and by 1951 more light was produced in the United States by fluorescents than by incandescents.
The main principle of fluorescent tube operation is based around inelastic scattering of electrons. In Particle physics and Chemistry, inelastic scattering is a fundamental Scattering process in which the kinetic energy of an incident particle is not conserved An incident electron (emitted from the coating on the coils of wire forming the cathode electrode) collides with an atom in the gas (such as mercury, argon or krypton) used as the ultraviolet emitter. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device If the free electron has enough kinetic energy, it can transfer some, or all, of that energy to the atom's outer electron, causing that electron to temporarily jump up to a higher energy level. The kinetic energy of an object is the extra Energy which it possesses due to its motion A quantum mechanical system or particle that is bound, confined spacially can only take on certain discrete values of energy as opposed to classical particles which This is why the collision is called 'inelastic,' as some of the energy is transferred. This higher energy state is unstable, and the atom will emit an ultraviolet photon as the atom's electron reverts to a lower, more stable, energy level. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The photons that are released from the chosen gas mixtures tend to have a wavelength in the ultraviolet part of the spectrum. This is not visible to the human eye, so must be converted into visible light. This is done by making use of fluorescence. Fluorescence is a Luminescence that is mostly found as an This fluorescent conversion occurs in the phosphor coating on the inner surface of the fluorescent tube, where the ultraviolet photons are absorbed by electrons in the phosphor's atoms, causing a similar energy jump, then drop, with emission of a further photon. The photon that is emitted from this second interaction has a lower energy than the one that caused it. The chemicals that make up the phosphor are specially chosen so that these emitted photons are at wavelengths visible to the human eye. The difference in energy between the absorbed ultra-violet photon and the emitted visible light photon goes to heat up the phosphor coating.
A fluorescent lamp is filled with a gas containing low pressure mercury vapor and argon (or xenon), or more rarely argon-neon, or sometimes even krypton. This page is about the physical properties of gas as a state of matter This article pertains to the chemical element For other uses see Argon (disambiguation. Xenon (ˈzɛnɒn or) is a Chemical element represented by the symbol Xe. Neon (ˈniːɒn is the Chemical element that has the symbol Ne and Atomic number 10 Krypton (ˈkrɪptən or /ˈkrɪptɒn/ from kryptos "hidden" is a Chemical element with the symbol Kr and Atomic number 36 The inner surface of the bulb is coated with a fluorescent (and often slightly phosphorescent) coating made of varying blends of metallic and rare-earth phosphor salts. Fluorescence is a Luminescence that is mostly found as an Phosphorescence is a specific type of Photoluminescence related to fluorescence. The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely A phosphor is a substance that exhibits the phenomenon of Phosphorescence (sustained glowing after exposure to energized particles such as Electrons Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants The bulb's cathode is typically made of coiled tungsten which is coated with a mixture of barium, strontium and calcium oxides (chosen to have a relatively low thermionic emission temperature). Tungsten (ˈtʌŋstən also known as wolfram (/ˈwʊlfrəm/ is a Chemical element that has the symbol W and Atomic number 74 Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy When the light is turned on, the electric power heats up the cathode enough for it to emit electrons. These electrons collide with and ionize noble gas atoms in the bulb surrounding the filament to form a plasma by a process of impact ionization. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity In Physics and Chemistry, plasma is an Ionized Gas, in which a certain proportion of Electrons are free rather than being bound Impact ionization is the process in a material by which one energetic Charge carrier can lose energy by the creation of other charge carriers
As a result of avalanche ionization, the conductivity of the ionized gas rapidly rises, allowing higher currents to flow through the lamp. An electron avalanche is a process in which a number of Free electrons in a medium (usually a Gas) are subjected to strong acceleration by an Electric The mercury, which exists at a stable vapor pressure equilibrium point of about one part per thousand in the inside of the tube (with the noble gas pressure typically being about 0. 3% of standard atmospheric pressure), is then likewise ionized, causing it to emit light in the ultraviolet (UV) region of the spectrum predominantly at wavelengths of 253. Ultraviolet ( UV) light is Electromagnetic radiation with a Wavelength shorter than that of Visible light, but longer than X-rays In Physics wavelength is the distance between repeating units of a propagating Wave of a given Frequency. 7 nm and 185 nm. A nanometre ( American spelling: nanometer, symbol nm) ( Greek: νάνος nanos dwarf; μετρώ metrό count) is a The efficiency of fluorescent lighting owes much to the fact that low pressure mercury discharges emit about 65% of their total light at the 254 nm line (also about 10-20% of the light emitted in UV is at the 185 nm line). The UV light is absorbed by the bulb's fluorescent coating, which re-radiates the energy at longer wavelengths to emit visible light. In Physics, absorption of electromagnetic radiation is the process by which the Energy of a Photon is taken up by matter typically the electrons of an Electromagnetic radiation takes the form of self-propagating Waves in a Vacuum or in Matter. The blend of phosphors controls the color of the light, and along with the bulb's glass prevents the harmful UV light from escaping. Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many
Fluorescent lamps are negative differential resistance devices, so as more current flows through them, the electrical resistance of the fluorescent lamp drops, allowing even more current to flow. Negative resistance (or negative differential resistance (NDR or differential negative resistance (DNR is a property of Electrical circuit elements composed Connected directly to a constant-voltage mains power line, a fluorescent lamp would rapidly self-destruct due to the uncontrolled current flow. Electrical tension (or voltage after its SI unit, the Volt) is the difference of electrical potential between two points of an electrical To prevent this, fluorescent lamps must use an auxiliary device, a ballast, to regulate the current flow through the tube; and to provide a higher voltage for starting the lamp. An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric
While the ballast could be (and occasionally is) as simple as a resistor, substantial power is wasted in a resistive ballast so ballasts usually use an inductor instead. |- align = "center"| |width = "25"| | |- align = "center"| || Potentiometer |- align = "center"| | | |- align = "center"| Resistor| | An inductor is a passive electrical component designed to provide Inductance in a circuit For operation from AC mains voltage, the use of simple magnetic ballast is common. In countries that use 120 V AC mains, the mains voltage is insufficient to light large fluorescent lamps so the ballast for these larger fluorescent lamps is often a step-up autotransformer with substantial leakage inductance (so as to limit the current flow). The volt (symbol V) is the SI derived unit of electric Potential difference or Electromotive force. An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors Leakage inductance is that property of an electrical Transformer that causes a winding to appear to have some inductance in series with the mutually-coupled Either form of inductive ballast may also include a capacitor for power factor correction. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors Many different circuits have been used to start and run fluorescent lamps. The choice of circuit is based on many factors such as mains voltage, tube length, initial cost, long term cost, instant verses non-instant starting, local customs, temperature ranges and parts availability, etc. The names of these different circuits vary by country and this can cause confusion. For example, pre-heat in this context has valid but different meanings in the US and elsewhere.
In the past, fluorescent lamps were occasionally run directly from a DC supply of sufficient voltage to strike an arc. Direct current ( DC) is the unidirectional flow of Electric charge. The ballast must have been resistive rather than reactive, leading to power losses in the ballast resistor (a resistive ballast would dissipate about as much power as the lamp). Also, when operated directly from DC, the polarity of the supply to the lamp must be reversed every time the lamp is started; otherwise, the mercury accumulates at one end of the tube. Fluorescent lamps are essentially never operated directly from DC; instead, an inverter converts the DC into AC and provides the current-limiting function as described below for electronic ballasts.
For line operation, ballasts may employ transistors or other semiconductor components to convert mains voltage into high-frequency AC while also regulating the current flow in the lamp. In Electronics, a transistor is a Semiconductor device commonly used to amplify or switch electronic signals A semiconductor' is a Solid material that has Electrical conductivity in between a conductor and an insulator; it can vary over that Frequency is a measure of the number of occurrences of a repeating event per unit Time. An alternating current ( AC) is an Electric current whose direction reverses cyclically as opposed to Direct current, whose direction remains constant These are referred to as "electronic ballasts", and take advantage of the higher efficacy of lamps operated with higher-frequency current. Electronics refers to the flow of charge (moving Electrons through Nonmetal conductors (mainly Semiconductors, whereas electrical
Fluorescent lamps which operate directly from mains frequency AC will flicker at twice the mains frequency, since the power being delivered to the lamp drops to zero twice per cycle. This means the light flickers at 120 times per second (Hz) in countries which use 60-cycle-per-second (60 Hz) AC, and 100 times per second in those which use 50 Hz. If the lamp has a magnetic ballast, this may also emit a humming sound. Magnetic ballasts are usually filled with a tarry potting compound to reduce emitted noise. Both the hum and flicker are eliminated in lamps which use a high-frequency electronic ballast, such as the increasingly popular compact fluorescent lamp.
In some circumstances, fluorescent lamps operated at mains frequency can also produce flicker at the mains frequency (50 or 60 Hz) itself, which is noticeable by more people. This can happen in the last few hours of tube life when the cathode emission coating at one end is almost run out, and that cathode starts having difficulty emitting enough electrons into the gas fill, resulting in slight rectification and hence uneven light output in positive and negative going mains cycles. A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J A rectifier is an electrical device that converts Alternating current (AC to Direct current (DC a process known as rectification. Mains frequency flicker can also sometimes be emitted from the very ends of the tubes, as a result of each tube electrode alternately operating as an anode and cathode each half mains cycle, and producing slightly different light output pattern in anode or cathode mode. An anode is an Electrode through which Electric current flows into a polarized electrical device A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device Flicker at mains frequency is more noticeable in the peripheral vision than it is in the center of gaze. Peripheral vision is a part of vision that occurs outside the very center of gaze
New fluorescent lamps may show a twisting spiral pattern of light in a part of the lamp. This effect is due to loose cathode material and usually disappears after a few hours of operation. 
The efficacy of fluorescent tubes ranges from about 16 lumens/watt for a 4 watt tube with an ordinary ballast to as high as about 100 lumens/watt for a 32 watt tube with modern electronic ballast, commonly averaging 50 to 67 lm/W overall. Efficacy is the capacity to produce a desired size of an effect under Ideal or Optimal conditions Most compact fluorescents 13 watts or more with integral electronic ballasts achieve about 60 lumens/watt. Due to phosphor degradation as they age, the average brightness over the entire service life is actually about 10% less. Lamps are rated by lumens after 100 hours of operation.  For a given fluorescent tube, a modern high-frequency electronic ballast gives about 10% efficacy improvement over an inductive ballast.
The mercury atoms in the fluorescent tube must be ionized before the arc can "strike" within the tube. For small lamps, it does not take much voltage to strike the arc and starting the lamp presents no problem, but larger tubes require a substantial voltage (in the range of a thousand volts).
In some cases, that is exactly how it is done: instant start fluorescent tubes simply use a high enough voltage to break down the gas and mercury column and thereby start arc conduction. These tubes can be identified by
In other cases, a separate starting aid must be provided. Some fluorescent designs (preheat lamps) use a combination filament/cathode at each end of the lamp in conjunction with a mechanical or automatic switch (see photo) that initially connect the filaments in series with the ballast and thereby preheat the filaments prior to striking the arc. An electrical filament is a thread of Metal, usually Tungsten, which is used to convert Electricity into light in Incandescent light bulbs (as developed A cathode is an Electrode through which (positive Electric current flows out of a polarized electrical device This is the oldest type of fluorescent lamp.
These systems are standard equipment in 240 V countries, and generally use a glow starter. Before the 1960s, four-pin thermal starters and manual switches were also used. Electronic starters are also sometimes used with these electromagnetic ballast fittings. In Japan, which operates on 100V and 50Hz, these systems are called glow bulbs. For a topic outline on this subject see List of basic Japan topics.
The automatic glow starter shown in the photograph consists of a small gas-discharge tube, containing neon and/or argon and fitted with a bi-metallic electrode. A bi-metallic strip is used to convert a temperature change into mechanical displacement The special bi-metallic electrode is the key to the automatic starting mechanism.
When starting the lamp, a glow discharge will appear over the electrodes of the starter. This glow discharge will heat the gas and cause the bi-metallic electrode to bend towards the other electrode. When the electrodes touch, the two filaments of the fluorescent lamp and the ballast will effectively be switched in series to the supply voltage. This causes the filaments to glow and emit electrons into the gas column by thermionic emission. Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy In the starter's tube, the touching electrodes have stopped the glow discharge, causing the gas to cool down again. The bi-metallic electrode also cools down and starts to move back. When the electrodes separate, the inductive kick from the ballast provides the high voltage to start the lamp. A snubber is a device used to suppress ("snub" voltage transients in electrical systems pressure transients in fluid systems or excess force or rapid movement in mechanical The starter additionally has a capacitor wired in parallel to its gas-discharge tube, in order to prolong the electrode life. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors
Tube strike is reliable in these systems, but glow starters will often cycle a few times before letting the tube stay lit, which causes objectionable flashing during starting. The older thermal starters behaved better in this respect. Once the tube is struck, the impinging main discharge then keeps the filament/cathode hot, permitting continued emission.
If the tube fails to strike, or strikes but then extinguishes, the starting sequence is repeated. With automated starters such as glowstarters, a failing tube will thus cycle endlessly, flashing as the starter repeatedly starts the worn-out lamp, and the lamp then quickly goes out as emission is insufficient to keep the cathodes hot, and lamp current is too low to keep the glowstarter open. This causes flickering, and runs the ballast at above design temperature. Turning the glowstarter a quarter turn anticlockwise will disconnect it, opening the circuit.
Some more advanced starters time out in this situation, and do not attempt repeated starts until power is reset. Some older systems used a thermal overcurrent trip to detect repeated starting attempts. These require manual reset.
Newer rapid start ballast designs provide filament power windings within the ballast; these rapidly and continuously warm the filaments/cathodes using low-voltage AC. No inductive voltage spike is produced for starting, so the lamps must usually be mounted near a grounded (earthed) reflector to allow the glow discharge to propagate through the tube and initiate the arc discharge.
Electronic ballasts often revert to a style in-between the preheat and rapid-start styles: a capacitor (or sometimes an autodisconnecting circuit) may complete the circuit between the two filaments, providing filament preheating. When the tube lights, the voltage and frequency across the tube and capacitor typically both drop, thus capacitor current falls to a low but non-zero value. Generally this capacitor and the inductor, which provides current limiting in normal operation, form a resonant circuit, increasing the voltage across the lamp so it can easily start. In Physics, resonance is the tendency of a system to Oscillate at maximum Amplitude at certain frequencies, known as the system's
Some electronic ballasts use programmed start. The output AC frequency is started above the resonance frequency of the output circuit of the ballast; and after the filaments are heated, the frequency is rapidly decreased. Frequency is a measure of the number of occurrences of a repeating event per unit Time. If the frequency approaches the resonant frequency of the ballast, the output voltage will increase so much that the lamp will ignite. In Physics, resonance is the tendency of a system to Oscillate at maximum Amplitude at certain frequencies, known as the system's If the lamp does not ignite, an electronic circuit stops the operation of the ballast.
Beginning in the 1990s a new type of ballast came into the mainstream, with a more expensive but significantly more efficient design: high frequency operation. These newer design high frequency ballasts have been used with either rapid start or pre-heat cathode/anode style lamps (with pins shorted at the lamp end), and use high frequency to excite the mercury within the lamp. These newer electronic ballasts convert the 50 or 60 hertz coming into the ballast to an output frequency in excess of 100 kHz. This allows for a more efficient system that generates less waste heat and requires significantly less power to light the lamp, and operates in a rapid starting manner. These are used in several applications, including new generation tanning lamp systems, whereby a 100 watt lamp (i. Tanning lamps (sometimes called tanning bulbs in the United States or tanning tubes in Europe are the part of a tanning bed booth or other tanning device which e. , F71T12BP) can be lighted using 65 to 70 watts of actual power while obtaining the same lumens as traditional ballasts at full power. These operate with voltages that can be almost 600 volts, requiring some consideration in housing design, and can cause a minor limitation in the length of the wire leads from the ballast to the lamp ends. These ballasts run just a few degrees above ambient temperature, which is partly why they are more efficient and allows them to be used in applications that would be inappropriate for hotter running electronics.
The end of life failure mode for fluorescent lamps varies depending how they are used and their control gear type. There are three main failure modes currently, and a fourth which is starting to appear:
The "emission mix" on the tube filaments/cathodes is necessary to enable electrons to pass into the gas via thermionic emission at the tube operating voltages used. Thermionic emission is the flow of Charge carriers from a surface or over some other kind of Electrical potential barrier caused by thermal vibrational energy The mix is slowly sputtered off by bombardment with electrons and mercury ions during operation, but a larger amount is sputtered off each time the tube is started with cold cathodes. Sputtering is a process whereby Atoms are Ejected from a solid target material due to bombardment of the target by energetic Ions It is commonly used for (The method of starting the lamp and hence the control gear type has a significant impact on this. ) Lamps operated for typically less than 3 hours each switch-on will normally run out of the emission mix before other parts of the lamp fail. The sputtered emission mix forms the dark marks at the tube ends seen in old tubes. When all the emission mix is gone, the cathode cannot pass sufficient electrons into the gas fill to maintain the discharge at the designed tube operating voltage. Ideally, the control gear should shut down the tube when this happens. However, some control gear will provide sufficient increased voltage to continue operating the tube in cold cathode mode, which will cause overheating of the tube end and rapid disintegration of the electrodes and their support wires until they are completely gone or the glass cracks, wrecking the low pressure gas fill and stopping the gas discharge. A cold cathode is an element used within some Nixie tubes Gas discharge lamps Gas filled tubes and Vacuum tubes Cold cathodes do not
This is only relevant to compact fluorescent lamps with integral electrical ballasts. An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric Ballast electronics failure is a somewhat random process which follows the standard failure profile for any electronic devices. Integral electronic ballasts suffer from shortened lifespans in high humidity applications. There is an initial small peak of early failures, followed by a drop and steady increase over lamp life. Life of electronics is heavily dependent on operating temperature—it typically halves for each 10 °C temperature rise. The quoted average life of a lamp is usually at 25 °C ambient (this may vary by country). The average life of the electronics at this temperature is normally greater than this, so at this temperature, not many lamps will fail due to failure of the electronics. In some fittings, the ambient temperature could be well above this, in which case failure of the electronics may become the predominant failure mechanism. Similarly, running a compact fluorescent lamp base-up will result in hotter electronics and shorter average life (particularly with higher power rated ones). Electronic ballasts should be designed to shut down the tube when the emission mix runs out as described above. In the case of integral electronic ballasts, since they never have to work again, this is sometimes done by having them deliberately burn out some component to permanently cease operation.
The phosphor drops off in efficiency during use. By around 25,000 operating hours, it will typically be half the brightness of a new lamp (although some manufacturers claim much longer half-lives for their lamps). Lamps which do not suffer failures of the emission mix or integral ballast electronics will eventually develop this failure mode. They still work, but have become dim and inefficient. The process is slow, and often only becomes obvious when a new lamp is operating next to an old lamp.
Mercury is lost from the gas fill throughout the lamp life, as it is slowly absorbed into glass, phosphor, and tube electrodes, where it can no longer function. Historically this hasn't been a problem because tubes have had an excess of mercury. However, environmental concerns are now resulting in low mercury content tubes which are much more accurately dosed with just enough mercury to last the expected life of the lamp. This means that loss of mercury will take over from failure of the phosphor in some lamps. The failure symptom is similar, except loss of mercury initially causes an extended run-up time (time to reach full light output), and finally causes the lamp to glow a dim pink when the mercury runs out and the argon base gas takes over as the primary discharge.
Some people find the color rendition produced by some fluorescent lamps to be harsh and displeasing. A healthy person can sometimes appear to have an unhealthy skin tone under fluorescent lighting. The extent to which this phenomenon occurs is related to the light's spectral composition, and may be gauged by its Color Rendering Index (CRI). The CIE color rendering index ( CRI) (or colour rendering index in British-style spelling sometimes called color rendition index) is a quantitative
CRI is a measure of how well balanced the different color components of the white light are, relative to daylight or a blackbody. By definition, an incandescent lamp has a CRI of 100. Real-life fluorescent tubes achieve CRIs of anywhere from 50% to 99%. Fluorescent lamps with low CRI have phosphors which emit too little red light. Skin appears less pink, and hence "unhealthy" compared with incandescent lighting. Colored objects appear muted. For example, a low CRI 6800K halophosphate tube (an extreme example)will make reds appear dull red or even brown.
Correlated color temperature (CCT) is a measure of the "shade" of whiteness of a light source, again by comparison with a blackbody. Color temperature is a characteristic of Visible light that has important applications in lighting photography videography publishing and other fields Typical incandescent lighting is 2700K which is yellowish-white. Halogen lighting is 3000K. Fluorescent lamps are manufactured to a chosen CCT by altering the mixture of phosphors inside the tube. Warm-white fluorescents have CCT of 2700K and are popular for residential lighting. Neutral-white fluorescents have a CCT of 3000K or 3500K. Cool-white fluorescents have a CCT of 4100K and are popular for office lighting. Daylight fluorescents have a CCT of 5000K to 6500K, which is bluish-white.
High CCT lighting generally requires higher light levels. At dimmer illumination levels, the human eye perceives lower color temperatures as more natural, as related through the Kruithof curve. Named after the Dutch engineer Arie Andries Kruithof the Kruithof curve relates the Illuminance and Colour temperature of visually-pleasing light sources So, a dim 2700K incandescent lamp appears natural, and a bright 5000K lamp also appears natural, but a dim 5000K fluorescent lamp appears too pale. Daylight-type fluorescents look natural only if they are very bright.
Some of the least pleasant light comes from tubes containing the older halophosphate type phosphors (chemical formula Ca5(PO4)3(F,Cl):Sb3+,Mn2+). A phosphor is a substance that exhibits the phenomenon of Phosphorescence (sustained glowing after exposure to energized particles such as Electrons Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Phosphorus, (ˈfɒsfərəs is the Chemical element that has the symbol P and Atomic number 15 Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Antimony (IPA (Received Pronunciation, /ˈæntɪmoʊni/ (US is a Chemical element with the symbol Sb (stibium meaning "mark" and Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. The bad color reproduction is due to the fact that this phosphor mainly emits yellow and blue light, and relatively little green and red. In the absence a reference, this mixture appears white to the eye, but the light has an incomplete spectrum. A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The CRI of such lamps is around 60.
Since the 1990s, higher quality fluorescent lamps use either a higher CRI halophosphate coating, or a triphosphor mixture, based on europium and terbium ions, that have emission bands more evenly distributed over the spectrum of visible light. Europium (jʊˈroʊpiəm is a Chemical element with the symbol Eu and Atomic number 63 Terbium (ˈtɝbiəm is a Chemical element with the symbol Tb and Atomic number 65 High CRI halophosphate and triphosphor tubes give a more natural color reproduction to the human eye. The CRI of such lamps is typically 82-100.
|Fluorescent lamp spectra|
|Typical fluorescent lamp with "rare earth" phosphor||A typical "cool white" fluorescent lamp utilizing two rare earth doped phosphors, Tb3+, Ce3+:LaPO4 for green and blue emission and Eu:Y2O3 for red. Rare earth elements and rare earth metals are according to IUPAC, the collection of seventeen Chemical elements in the Periodic table, namely Lanthanum (ˈlænθənəm is a Chemical element with the symbol La and Atomic number 57 For an explanation of the origin of the individual peaks click on the image. Note that several of the spectral peaks are directly generated from the mercury arc. This is likely the most common type of fluorescent lamp in use today.|
|An older style halophosphate phosphor fluorescent lamp||Halophosphate phosphors in these lamps usually consist of trivalent antimony and divalent manganese doped calcium halophosphate (Ca5(PO4)3(Cl,F):Sb3+, Mn2+). Antimony (IPA (Received Pronunciation, /ˈæntɪmoʊni/ (US is a Chemical element with the symbol Sb (stibium meaning "mark" and Manganese (ˈmæŋgəniːz is a Chemical element, designated by the symbol Mn. Calcium (ˈkælsiəm is the Chemical element with the symbol Ca and Atomic number 20 Chlorine (ˈklɔriːn from the Greek word 'χλωρóς' ( khlôros, meaning 'pale green' is the Chemical element with Atomic number 17 and Fluorine, fluorum meaning "to flow" is the Chemical element with the symbol F and Atomic number 9 The color of the light output can be adjusted by altering the ratio of the blue emitting antimony dopant and orange emitting manganese dopant. The color rendering ability of these older style lamps is quite poor. Halophosphate phosphors were invented by A. H. McKeag et al in 1942.|
|"Natural sunshine" fluorescent light||An explanation of the origin of the peaks is on the image page.|
|Yellow fluorescent lights||The spectrum is nearly identical to a normal fluorescent bulb except for a near total lack of light below 500 nanometers. This effect can be achieved through either specialized phosphor use or more commonly by the use of a simple yellow light filter. These lamps are commonly used as lighting for photolithography work in cleanrooms and as "bug repellant" outdoor lighting (the efficacy of which is questionable). Photolithography (also called optical lithography) is a process used in Microfabrication to selectively remove parts of a thin film (or the bulk of a substrate A cleanroom is an environment typically used in Manufacturing or scientific research that has a low level of environmental Pollutants such as dust airborne|
|Spectrum of a "blacklight" bulb||There is typically only one phosphor present in a blacklight bulb, usually consisting of europium-doped strontium fluoroborate which is contained in an envelope of Wood's glass. A Black light or UV Light is a lamp emitting Electromagnetic radiation that is almost exclusively in the soft near ultraviolet range and emits Europium (jʊˈroʊpiəm is a Chemical element with the symbol Eu and Atomic number 63 Strontium (ˈstrɒntiəm /ˈstrɒnʃiəm/) is a Chemical element with the symbol Sr and the Atomic number 38 Borates in Chemistry are Chemical compounds containing Boron bonded to three Oxygen atoms written as B(OR3 Wood's glass was developed by Robert Williams Wood (1868&ndash1955 as a light filter used in communications during World War I.|
Fluorescent light bulbs come in many shapes and sizes. The compact fluorescent light bulb (CF) is becoming more popular. Many compact fluorescent lamps integrate the auxiliary electronics into the base of the lamp, allowing them to fit into a regular light bulb socket.
In the US, residential use of fluorescent lighting remains low (generally limited to kitchens, basements, hallways and other areas), but schools and businesses find the cost savings of fluorescents to be significant and rarely use incandescent lights. Within a urban area there is a tendency for land uses to Aggregate. For the Banana Yashimoto novel see Kitchen (novel A kitchen, is a room or part of a room (sometimes called "kitchen A basement is one or more floors of a building that are either completely or partially below the Ground floor. Several things are commonly known as Halls or halls. For the development of meaning of the word 'hall' see Hall (concept. A school (from Greek σχολεῖον - scholeion) is an Institution designed to allow and encourage Students (or "pupils" A business (also called firm or an enterprise) is a legally recognized organizational entity designed to provide goods and/or services to
Lighting arrangements use fluorescent tubes in an assortment of tints of white. Sometimes this is because of the lack of appreciation for the difference or importance of differing tube types. Mixing tube types within fittings improves the color reproduction of lower quality tubes. Tax incentives and environmental awareness result in higher use in places such as California. California ( is a US state on the West Coast of the United States, along the Pacific Ocean.
In other countries, residential use of fluorescent lighting varies depending on the price of energy, financial and environmental concerns of the local population, and acceptability of the light output. In East and Southeast Asia it is very rare to see incandescent bulbs in buildings anywhere. Incandescence is the emission of Light (visible Electromagnetic radiation) from a hot body due to its temperature
In February 2007, Australia enacted a law that will ban most sales of incandescent light bulbs by 2010. For a topic outline on this subject see List of basic Australia topics.  While the law does not specify which alternative Australians are to use, compact fluorescents are likely to be the primary replacements. In April 2007, Canada announced a similar plan to phase out the sale of incandescent bulbs by 2012. Finnish parliament has been discussing banning sales of incandescent light bulbs by the beginning of 2011. 
Fluorescent lamps are more efficient than incandescent light bulbs of an equivalent brightness. Luminous efficacy is a property of Light sources which indicates what portion of the emitted Electromagnetic radiation is usable for human vision. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general This is because a greater proportion of the power used is converted to usable light and a smaller proportion is converted to heat, allowing fluorescent lamps to run cooler. Light, or visible light, is Electromagnetic radiation of a Wavelength that is visible to the Human eye (about 400–700 In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature A typical 100 Watt tungsten filament incandescent lamp may convert only 10% of its power input to visible white light, whereas typical fluorescent lamps convert about 22% of the power input to visible white light  - see the table in the luminous efficacy article. Luminous efficacy is a property of Light sources which indicates what portion of the emitted Electromagnetic radiation is usable for human vision. Typically a fluorescent lamp will last between 10 to 20 times as long as an equivalent incandescent lamp when operated several hours at a time. Consumer experience suggests that the lifetime is much lower when operated for very short frequent intervals.
The higher initial cost of a fluorescent lamp is usually more than compensated for by lower energy consumption over its life. The longer life may also reduce lamp replacement costs, providing additional saving especially where labour is costly. Therefore they are widely used by businesses and institutions, but not as much by households.
If a fluorescent lamp is broken, mercury can contaminate the surrounding environment. A 1987 report described a 23-month-old toddler hospitalized due to mercury poisoning traced to a carton of 8-foot fluorescent lamps that had broken. Mercury poisoning (also known as mercurialism, hydrargyria, Hunter-Russell syndrome, or acrodynia when affecting children is a Disease The glass was cleaned up and discarded, but the child often used the area for play. 
Fluorescent lamps can cause problems among individuals with pathological sensitivity to ultraviolet light. They can induce disease activity in photosensitive individuals with Systemic lupus erythematosus; standard acrylic diffusers absorb UV-B radiation and appear to protect against this. Systemic lupus erythematosus ( SLE or lupus,) is a chronic autoimmune disease that can be fatal though with recent medical advances fatalities are becoming  In rare cases individuals with solar urticaria (allergy to sunlight) can get a rash from fluorescent lighting.  However, no fluorescent lighting technology presents anywhere near the high levels of UV danger to light sensitive persons that sunlight presents. A recent study in the US found that UV exposure from sitting under typical office fluorescent lights for eight continuous hours is equivalent to just over one minute of sun exposure (Lytle et al An Estimation of Squamous Cell Carcinoma Risk from Ultraviolet Radiation Emitted by Fluorescent Lamps; Photodermatol Photoimmunol Photomed (1993))
Elimination of fluorescent lighting is appropriate for several conditions. In addition to causing headache and fatigue, and problems with light sensitivity, they are listed as problematic for individuals with epilepsy, lupus, chronic fatigue syndrome, and vertigo (related to cardiovascular problems, MS, and several other disorders. A headache ( cephalalgia in medical terminology is a condition of pain in the Head; sometimes Neck or upper back pain may also be interpreted Epilepsy is a common chronic Neurological disorder that is characterized by recurrent unprovoked seizures. Chronic fatigue syndrome ( CFS) is the most common name given to a poorly understood variably debilitating disorder or disorders of uncertain causation Vertigo (from the Latin vertere, to turn and the suffix -igo, a condition i ) Research on this is very limited.
Fluorescent lamps require a ballast to stabilize the lamp and to provide the initial striking voltage required to start the arc discharge. The power factor of an AC electric power system is defined as the Ratio of the real power to the apparent power, and is a number between 0 and This increases the cost of fluorescent light fixtures, though often one ballast is shared between two or more lamps. A light fixture is an electrical device used to create artificial light or illumination Electromagnetic ballasts with a minor fault can produce an audible humming or buzzing noise.
Simple inductive fluorescent lamp ballasts have a power factor of less than unity. The power factor of an AC electric power system is defined as the Ratio of the real power to the apparent power, and is a number between 0 and Inductive ballasts include power factor correction capacitors.
Fluorescent lamps are a non-linear load and generate harmonics on the electrical power supply. This can generate radio frequency noise in some cases. Suppression of harmonic generation is standard practice, but imperfect. Very good suppression is possible, but adds to the cost of the fluorescent fixtures.
Fluorescent lamps operate best around room temperature (say, 20 °C or 68 °F). At much lower or higher temperatures, efficiency decreases and at low temperatures (below freezing) standard lamps may not start. Special lamps may be needed for reliable service outdoors in cold weather. A "cold start" electrical circuit was also developed in the mid-1970s.
Because the arc is quite long relative to higher-pressure discharge lamps, the amount of light emitted per unit of surface of the lamps is low, so tube lamps were large compared with incandescent sources. However, in many cases low luminous intensity of the emitting surface was useful because it reduced glare. Glare is difficulty seeing in the presence of bright Light such as direct or reflected Sunlight or artificial light such as car Headlamps at night The bulk created by this lamp affected the design of fixtures since light must be directed from long tubes instead of a compact source.
Recently, a new type of fluorescent lamp, the CFL, has been introduced to address this issue and allow regular incandescent sockets to be fitted with this type of lamp, thereby negating the need to mount it on special fixtures. However, some CFLs intended to replace incandescents will not fit some desk lamps, because the harp (heavy wire shade support bracket) is shaped for the narrow neck of an incandescent lamp. CFLs tend to have a wide housing for their electronic ballast close to the lamp's base, too wide to fit.
Older fluorescent fittings using an electromagnetic mains frequency ballast do not give out a steady light; instead, they flicker (fluctuate in intensity) at twice the supply frequency. While this is not easily discernible by the human eye, it can cause a strobe effect posing a safety hazard in a workshop for example, where something spinning at just the right speed may appear stationary if illuminated solely by a single fluorescent lamp; this effect is entirely eliminated by paired lamps operating on a lead-lag ballast. Temporal aliasing is the term applied to a visual Phenomenon also known as the stroboscopic effect. Older electromagnetic ballasts may also causes problems for video recording as there can be a 'beat effect' between the periodic reading of a camera's sensor and the fluctuations in intensity of the fluorescent lamp. When other devices that also flicker, such as CRT-based computer monitors, are operated under fluorescent lighting, the flicker may become much more noticeable. The cathode ray tube (CRT is a Vacuum tube containing an Electron gun (a source of electrons and a Fluorescent screen with internal or
Incandescent lamps, due to the thermal inertia of their element, fluctuate to a lesser extent. The incandescent light bulb, incandescent lamp or incandescent light globe is a source of electric Light that works by Incandescence, (a general Volumetric heat capacity ( VHC) describes the ability of a given Volume of a substance to store Internal energy while undergoing a given Temperature This is also less of a problem with compact fluorescents, since they multiply the line frequency to levels that don't produce visible flicker. Installations can eliminate the stroboscope effect by using lead-lag ballasts, or by operating the lamps on different phases of a polyphase power supply. A stroboscope, also known as a strobe, is an instrument used to make a cyclically moving object appear to be slow-moving or stationary Electronic ballasts do not produce visible light flicker, since the phosphor persistence is longer than a half cycle of the higher operation frequency. Operating frequencies of electronic ballasts are selected to avoid interference with infrared remote controls.
Most new compact fluorescent lamps (CFLs) sold in the U. S. since 2006 have electronic ballasts that do not visibly flicker. The easiest way to tell if a CFL has an electromagnetic ballast is to pick it up. If the base is bulky, and it feels dense and heavy for its size, chances are it has an older, electromagnetic ballast. By contrast, a CFL with a small base that is lightweight for its size will likely have an electronic ballast. Some other clues are labels such as "rapid start" or "instant start", but these are inconsistent between manufacturers.
The non-visible 100 Hz - 120 Hz flicker from fluorescent tubes powered by electromagnetic ballasts are associated with headaches and eyestrain. Individuals with high flicker fusion threshold are particularly affected by electromagnetic ballasts: their EEG alpha waves are markedly attenuated and they perform office tasks with greater speed and decreased accuracy. The flicker fusion threshold (or flicker fusion rate) is a concept in the Psychophysics of vision. The problems are not observed with electronic ballasts.  Ordinary people have better reading performance using high frequency (20 kHz – 60 kHz) electronic ballasts than electromagnetic ballasts. 
The flicker of fluorescent lamps, even with electromagnetic ballasts, is so rapid that it is unlikely to present a hazard to individuals with epilepsy. Epilepsy is a common chronic Neurological disorder that is characterized by recurrent unprovoked seizures.  Early studies suspected a relationship between the flickering of fluorescent lamps with electromagnetic ballasts and repetitive movement in autistic children. A stereotypy (ˈstɛriəˌtаɪpi (plural stereotypies) is a repetitive or ritualistic movement posture or utterance found in patients with Mental retardation, Language development. The terminology  However, these studies had interpretive problems and have not been replicated.
The issues with color faithfulness of some tube types are discussed above.
Fluorescent light fixtures cannot be connected to a standard dimmer switch used for incandescent lamps. Dimmers are devices used to vary the brightness of a light. By decreasing or increasing the RMS voltage and hence the mean power to the lamp it is possible Two effects are responsible for this: the waveshape of the voltage emitted by a standard phase-control dimmer interacts badly with many ballasts and it becomes difficult to sustain an arc in the fluorescent tube at low power levels. Many installations require 4-pin fluorescent lamps and compatible dimming ballasts for successful fluorescent dimming. These systems keep the cathodes of the fluorescent tube fully heated even as the arc current is reduced, promoting easy thermionic emission of electrons into the arc stream. CFLs are available that work in a dimmer circuit.
The disposal of phosphor and particularly the mercury in the tubes is an environmental issue. Mercury (ˈmɜrkjʊri also called quicksilver or hydrargyrum, is a Chemical element with the symbol Hg ( Latinized hydrargyrum Mercury poses the greatest hazard to pregnant women, infants, and children. Governmental regulations in many areas require special disposal of fluorescent lamps separate from general and household wastes. For large commercial or industrial users of fluorescent lights, recycling services are available in many nations, and may be required by regulation. In some areas, recycling is also available to consumers. The need for a recycling infrastructure is an issue with instituting proposed bans of incandescent bulbs.
The amount of mercury in a standard lamp can vary dramatically, from 3 to 46 mg.  Newer lamps contain less mercury and the 3-4 mg versions are sold as low-mercury types. A typical 2006-era 4 ft (122 cm) T-12 fluorescent lamp (i. e. , F32T12) contains about 12 milligrams of mercury.  In early 2007, the National Electrical Manufacturers Association in the US announced that "Under the voluntary commitment, effective April 15, 2007, participating manufacturers will cap the total mercury content in CFLs under 25 watts at 5 milligrams (mg) per unit. CFLs that use 25 to 40 watts of electricity will have total mercury content capped at 6 mg per unit. "
A broken fluorescent tube is more hazardous than a broken conventional incandescent bulb due to the mercury content. Because of this, the safe cleanup of broken fluorescent bulbs differs from cleanup of conventional broken glass or incandescent bulbs. 99% of the mercury is typically contained in the phosphor, especially on lamps that are near their end of life. 
Lamps are typically identified by a code such as F##T##, where F is for fluorescent, the first number indicates the power in watts (or where lamps can be operated at different power levels, the length in inches), the T indicates that the shape of the bulb is tubular, and the last number is the diameter in eighths of an inch (sometimes in millimeters, rounded to the nearest millimeter). In Communications a code is a rule for converting a piece of Information (for example a letter, Word, Phrase, or Inches redirects here To see the Les Savy Fav album see Inches. Geometry, a diameter of a Circle is any straight Line segment that passes through the center of the circle and whose Endpoints are on the Typical diameters are T12 or T38 (11/2" Ø or 38. 1 mm Ø) for residential bulbs with old magnetic ballasts, T8 or T26 (1" Ø or 25. A magnet (from Greek grc μαγνήτης λίθος " Magnesian stone" is a material or object that produces a Magnetic field. An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric 4 mm Ø) for commercial energy-saving lamps with electronic ballasts, and T5 or T16 (5/8" Ø or 15. 875 mm Ø) for very small lamps which may even operate from a battery powered device.
|Fluorescent tube diameter designation comparison|
|Tube Diameter Designations||Tube Diameter Measurements|
|T5||T16||5/8" Ø||15. 875 mm Ø|
|T8||T26||8/8" Ø||1" Ø||25. 4 mm Ø|
|T9 *||T29 *||9/8" Ø *||11/8" Ø *||28. 575 mm Ø *|
|T12||T38||12/8" Ø||11/2" Ø||38. 1 mm Ø|
|PG17 **||N/A **||17/8" Ø **||21/8" Ø **||53. 975 mm Ø **|
|* - Circular fluorescent tubes only|
** - General Electric's Power Groove® tubes only
Some lamps are designed with a reflector built inside the lamp. This is done by pouring an opaque coating into the lamp first, rotating the lamp to achieve the desired amount of coverage, then allowing it to dry before adding the traditional phosphors. With straight lamps, this is commonly poured in a fashion as to cover half the lamp as it is lying flat, with the lamp rated as to the amount of curvature that is covered in the opaque coating. A 180 degree lamp has 50% coverage, whereas a 210 degree lamp has 30 degrees more coverage. These are the most common type, although the reflector can vary from 120 degrees to well over 310 degrees. Lamps that have significantly more than 210 degrees of coverage are often referred to as "aperature lamps" as the amount of open area that light can escape is significantly less than the area that acts as an internal reflector. Often, a lamp is marked as a reflector lamp by adding the letter "R" in the model code, so a F##T##HO lamp with a reflector would be coded as "FR##T##HO". VHO lamps with reflectors may be coded as VHOR. No such designation exists for the amount of reflector degrees the lamp has.
Reflector lamps are used in several application, particularly when light is only desired to be emitted in a single direction, or when an application requires the maximum amount of light. This can be as simple as in a higher end tanning bed or in some backlighting situation for electronics. A tanning bed or sunbed is a device emitting Ultraviolet radiation (typically 95% UVA and 5% UVB +/-3% used to produce a cosmetic tan. An internal reflector is more efficient than standard external reflectors as there is less opportunity to lose light due to wave cancellation. Another example is color matched aperature lights (330 degrees of opening, give or take) are used in the food industry for quality control purposes, to allow robotic inspection of cooked goods.
Slimline lamps operate on an instant start ballast and are recognizable by their single-pin bases.
High-output lamps are brighter and draw more electrical current, have different ends on the pins so they cannot be used in the wrong fixture, and are labeled F##T##HO, or F##T##VHO for very high output. Output is the term denoting either an exit or changes which exit a System and which activate/modify a Process. Electric current is the flow (movement of Electric charge. The SI unit of electric current is the Ampere. A pin is a device used for fastening objects or material together Since about the early to mid 1950s to today, General Electric developed and improved the Power Groove® lamp with the label F##PG17. These lamps are recognizable by their large diameter (17/8" or 21/8"), grooved tube shape and an R17d cap on each end of them.
U-shaped tubes are FB##T##, with the B meaning "bent". Most commonly, these have the same designations as linear tubes. Circular bulbs are FC##T#, with the diameter of the circle (not circumference or watts) being the first number, and the second number usually being 9 (29 mm) for standard fixtures. The circumference is the distance around a closed Curve. Circumference is a kind of Perimeter.
Color is usually indicated by WW for warm white, EW for enhanced (neutral) white, CW for cool white (the most common), and DW for the bluish daylight white. Daylight or the light of day is the combination of all direct and indirect Sunlight outdoors during the daytime (and perhaps Twilight) BLB is used for blacklight-blue lamps commonly used in bug zappers. A bug zapper is a device that attracts and kills Insects that are attracted by light BL is used for blacklight lamps commonly used in nightclubs. A Black light or UV Light is a lamp emitting Electromagnetic radiation that is almost exclusively in the soft near ultraviolet range and emits Other non-standard designations apply for plant lights or grow lights. A grow light is an Electric lamp designed to promote plant growth by emitting an Electromagnetic spectrum appropriate for Photosynthesis. A grow light is an Electric lamp designed to promote plant growth by emitting an Electromagnetic spectrum appropriate for Photosynthesis.
Philips and Osram use numeric color codes for the colors. Koninklijke Philips Electronics NV ( Royal Philips Electronics Inc. OSRAM is part of the industry sector of Siemens AG and one of the two leading lighting manufacturers in the world On Tri-Phosphor and Multi-Phosphor tubes, the first digit indicates the Color Rendition Index of the lamp. If the first digit on a lamp says 8, then the CRI of that lamp will be approximately 85. The last two digits indicate the Color Temperature of the lamp in Kelvins (°K). Color temperature is a characteristic of Visible light that has important applications in lighting photography videography publishing and other fields For example, if the last two digits on a lamp say 40, that lamp's Color Temperature will be 4000 °K, which is a common Tri-Phosphor Cool White fluorescent lamp.
|Numeric Color Code||Color||Approximate Color Rendition Index||Color Temperature (°K)|
|27||Warm White||50 - 79||2700|
|33||Cool White||50 - 79||4000|
|54||Cool Daylight||50 - 79||6000|
|Numeric Color Code||Color||Approximate Color Rendition Index||Color Temperature (°K)|
|Numeric Color Code||Color||Approximate Color Rendition Index||Color Temperature (°K)|
|Special purpose tubes|
|05||Germicidal lamps||No phosphors used at all,|
using an envelope of fused quartz. A germicidal lamp is a special type of lamp which produces Ultraviolet light (UVC Fused quartz and fused silica are types of Glass containing primarily Silica in amorphous (non- Crystalline form
|08||Black light lamps|
|09||Sun Tanning lamps|
Odd lengths are usually added after the color. A Black light or UV Light is a lamp emitting Electromagnetic radiation that is almost exclusively in the soft near ultraviolet range and emits Tanning lamps (sometimes called tanning bulbs in the United States or tanning tubes in Europe are the part of a tanning bed booth or other tanning device which One example is an F25T12/CW/33, meaning 25 Watts, 11/2" diameter, Cool White, 33" or 84 cm long. Without the 33", it would be assumed that an F25T12 is the more-common 30" long.
Some compact fluorescents are now being labelled with this designation system.
Fluorescent lamps can be illuminated by means other than a proper electrical connection. These other methods however result in very dim or very short-lived illumination, and so are seen mostly in science demonstrations. With the exception of static electricity, these methods can be very dangerous if done improperly:
Special fluorescent lights are often used in film and video production. For the science of static charges see Electrostatics Static electricity refers to the accumulation of excess Electric charge in a A Van de Graaff generator is an electrostatic machine which uses a moving belt to accumulate very high electrostatically stable Voltages on a hollow metal globe A Tesla coil is a type of resonant transformer circuit invented by Serbian-American scientist Nikola Tesla around 1891 In Electronics, capacitive coupling is the transfer of energy within an Electrical network by means of the Capacitance between circuit nodes Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power The brand name Kino Flo are used to create softer fill light and are less hot than traditional halogen light sources. These fluorescent lights are designed with special high-frequency ballasts to prevent video flickering and high color-rendition index bulbs to approximate daylight color temperatures.