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1St Cover April2017 Issue.Indd

1St Cover April2017 Issue.Indd

FEATURE ARTICLE KRISHNA MURTY KOMMAJOSYULA

Light on electric ! with his TheTh journey j of f electric l t i lightli ht hash beenb fascinating.f

Thomas Alva Edison later described he and his associate wrestled with the task of placing the carbonized cotton in the fi rst electric bulb: “All night Bachelor, my assistant, worked beside me. The next day and the next night again, and at the end of that time we had produced one out of an entire spool of Clarke’s thread. Having HE inventor was seated in his made it, it was necessary to take it to laboratory alone one evening, the glass-blower’s house. With the Tgloomy over his thousand- utmost precaution Bachelor took up the and-one disappointments. Though not precious carbon, and I marched after crushed in spirit, the frustration was him, as if guarding a mighty treasure. visible. He had worked with every To our consternation, just as we reached known material to make a workable the glass-blower’s bench the wretched fi lament for his electric bulb… and had carbon broke. We turned back to the failed. main laboratory and set to work again. Absentmindedly, his right hand It was late in the afternoon before we The incandescent picked up a little lampblack mixed had produced another carbon, which light bulb with tar lying on the table, left over was again broken by a jeweller’s from his earlier experiment on a screw-driver falling against it. But we . He began rolling turned back again, and before night the plant imaginable. He even contacted it between his fi nger and thumb… and carbon was completed and inserted in biologists who sent him plant fi bres while getting up, as he tried to clean his the lamp. The bulb was exhausted of air from faraway places. fi ngers he saw the thin thread. Soon his and sealed, the current turned on, and It seems, on a certain hot day in brilliant mind had an idea. Why not use the sight we had so long desired to see 1879, as Edison was fanning himself a fi lament for an incandescent lamp? met our eyes.” with a foldable oriental fan from Japan, That was the beginning of the Edison and Bachelor watched a fi ne bamboo piece got unwound from incandescent lamp that has lighted the electric lamp for forty-fi ve hours it. Inquisitive as he was, he carbonized up our homes for over hundred years until the light vanished. The weary the piece and tested it as a fi lament. He but now may soon be relegated to the men congratulated each other. Edison sent assistants to Japan to get the right museums. tested the carbonized fi laments of every type of bamboo.

37 SCIENCE REPORTER April 2017 The Savoy Theatre, London, was the fi rst public building to be lit up entirely by

Edison thus came to be known as A research in 2007 also concluded that patent litigation the courts decided in the inventor of . Scientists the Goebel-Defense was fraudulent. Edison’s favour in 1892 and forced around the world worked on the On 3 August 1874, Henry Westinghouse to stop production. incandescent lamp, improving their Woodward, a medical student and Similarly, William Sawyer extremely short lifespans, reducing cost Mathew Evans received a Canadian developed a system in 1877 and and improving effi ciency. patent for an electric light bulb. Their received patents with Albon Man. They Edison could outdo others because light bulb was a glass tube fi lled with soon formed Sawyer & Man Electric of his astute business sense, inert and had carbon fi lament. Co. Westinghouse contracted him to in developing an effective incandescent They fi led for a patent in the United light up the Chicago World’s Fair material, and availability of better States prior to Edison’s patent but in 1893. Sawyer successfully fought pumps and viable electrical failed to commercialize it. Shrewd against Edison. Westinghouse bought systems. But then, Edison was not the businessman that he was, Edison rights to the Sawyer-Man patents and fi rst. purchased the patent before he obtained started making based on those A British astronomer and chemist, his own patent. patents. De La Rue created the light bulb in 1820 In 1874, Alexander Lodygin In the late 1870’s, high school by passing an through received a Russian patent for the teachers, Elihu Thomson and Edwin a coil in a . The . He later moved Houston began experimenting and cost of the platinum made it impractical to the US and demonstrated a light bulb for commercial production. In 1893, with a fi lament at the newspapers reported that Henry Goebel World’s Fair in Paris in 1900. had developed incandescent light bulbs “If you want to succeed, get some 25 years earlier comparable to those enemies,” Edison was quoted as saying invented by Edison in 1879. But this in the Ladies Home Journal, April German scientist who migrated to the 1898. When he could not fi ght with his US did not apply for a patent. enemy, he made friends with them. But In May 1893, the Edison one up was who hired Electric Light Co. sued competitive Ludwig Boehm, Edison’s glassblower manufacturers for infringing their patent away from Menlo Park and quickly rights. However, the defence of these produced a lamp with a high-resistance companies claimed that Edison’s patent fi lament in 1880. Maxim lamps were was void because of the same invention made by his Electric by Goebel 25 years earlier. But judges Lighting Company for several years of four courts were convinced that there until the company was purchased by was no proof for the claimed invention. in 1888. In a

38 SCIENCE REPORTER April 2017 Then in 1904, insanely great but relatively unknown Charles P. Steinmetz replaced the carbon electrode with magnetite, a type of iron ore. The lamp life increased to 600 hours from 125 hours. But later, the Xenon short- extinguished the carbon arc lamp. Another serious competitor to the incandescent bulb then was the . Nernst Lamp effectively solved the fi lament bulb problems, emitted a natural light close to day light and was about twice as effi cient. It used a small ceramic rod, not electrically conductive at room . It was heated to by a separate heater fi lament. When its resistance dropped, Nernst lamp a would cut off power to the heater and all the current would fl ow through the glower. The ceramic did not oxidise like metal, and the glass established the American Electric States patent rights to the Brush Electric enclosure was dispensed with. Apart Company, which was renamed the Company in June 1882, which later from domestic illumination, Nernst Thomson-Houston Electric Company. merged into the Thomson-Houston lamps were made use of in fax systems, In 1886, this company purchased the Electric Company. for ophthalmology, for projection and Sawyer & Man Electric Company By 1890, Edison with his merged in microscopy. Walther Nernst won and began making incandescent lamps companies, Thomson-Houston, and the 1920 Nobel Prize in Chemistry. under the Sawyer-Man patents. Westinghouse were the “Big 3” of the Nobel Laureate, , Joseph Wilson Swan (1828- American lighting industry. In 1892, J. who studied under Nernst, helped him 1914), a physicist and chemist born in Pierpont Morgan engineered a merger develop the Nernst lamp. Sunderland, England created a “light between the Edison and Thomson- Industry giants had to double bulb” by enclosing carbonized paper Houston and was born. up their researches to face the threat fi lament in an evacuated glass bulb in Lewis Howard Latimer patented from Nernst lamps, then a craze with 1850. Though unsuccessful initially, a carbon fi lament with longer life. He the fashionable high and powerful Swan returned to his experiments as also created the threaded socket that mighty. Werner von Bolton in better vacuum pumps became available. allows a light bulb to fi t into the fi xture. Germany developed the He failed in his fi rst public attempt to Edison eventually purchased the patent fi lament with higher effi ciency and light up his incandescent carbon lamp at and hired Latimer in 1884. greater brightness. and a lecture for the and Frederick Halske Company marketed these bulbs Chemical Society on 18 December de Moleyns also tried their hand at successfully. Sensing a major threat, 1878. However, on 17 January 1879 creating an incandescent light. In the General Electric formed research labs he was successful and by 1880, he early 1800s, Sir Humphry Davy used and giants like Willis Whitney, William produced a 16-watt bulb that could last charcoal sticks and batteries to make D. Coolidge and Irving Langmuir were for 1500 hours. His house, in Gates the fi rst experimental arc lamp. The roped in. In 1903, Willis Whitney Head, England was lit up by electric two carbon rods must have just enough invented a metal-coated carbon fi lament light for the fi rst time in the world. gap to get the proper arc. A number with an improved effi ciency of 25%. Swan obtained a British patent of experiments were carried out to This fi lament would not blacken the and took Edison to court for patent improve the carbon rod life, adjustment inside of a light bulb and was used in infringement. Edison lost but as a of the gaps and use in domestic lighting. the famous lamps. part of the settlement Edison & Swan In 1876, Charles F. Brush In 1904, Alexander Just and Franz United Electric Light Company was invented a new type of simple, reliable, Hanaman (Austria) developed sintered born in 1883, popularly known as self-regulating arc lamp, as well as a with doubled the effi ciency. “Ediswan.” Ediswan sold lamps made new designed to power it and GE bought the rights in 1907. Tungsten with a cellulose fi lament that Swan had formed the Brush Electric Company in fi laments were until then brittle and not invented in 1881. Swan sold his United 1880. practical. It was to the credit of William

39 SCIENCE REPORTER April 2017 light. The life of the bulb increases Mazda lamp and it can be made smaller. But, to withstand higher , is often used for lamps. The incandescent lamp has been with us for around 120 years, in spite of Camera fl ash the tough fi ght from fl uorescent lamps. bulb But now, LEDs will fi nally move them to the museums. However, the classical bulb will continue to be the cartoon piece to depict, “That’s an idea!” For that matter, most of the present generation may not have seen D. Coolidge at GE who developed a the fl ash bulb. Watch an old black ductile tungsten wire in 1908 with high and movie to catch a glimpse strength, which is still the material of the photographer quickly changing used in the bulbs. Irving Langmuir the fl ashbulb while photographing the developed coiled coil fi laments, as well coronation of a queen or grand entry of as gas fi lling and doping of tungsten to a movie star. lengthen its life. It is just another incandescent Now, this brings us to the small light bulb where the fi lament was little lamp with extreme brightness, aluminum, magnesium or . the . Normally tungsten The of the fi lament is so atoms evaporate from the fi lament and low that it would burn out and vaporize, If you have seen the electric tester deposit on the inside of the bulb, thus intensifying the brightness. Early lamps – a small screw driver used to test the blackening the glass. The fi lament also would last just one fl ash. Timing the presence of electricity in the wiring – gets thinner, eventually breaks, ending fl ash to match the camera shutter was a you will fi nd a lamp that glows the life of the lamp. great challenge. to indicate presence of current. It was While working at General Electric, In 1929, Hauser Company in the pilot lamp in indicator lamps before Ohio in 1955, Elmer Friedrich along Germany released the Vacublitz, the advent of LEDs. The colorful with Emmett Wiley realized that a the fi rst true fl ashbulb made from signages in the shopping windows and small amount of iodine around the aluminum foil sealed in oxygen, by advertisement boards are neon . fi lament could make it burn at higher using Johannes Ostermeier’s patents. Georges Claude, French engineer and temperatures. Then the tungsten atoms In 1931, Harold Edgerton, professor inventor, also known as “the Edison of chemically unite with the halogen gas of electrical engineering produced the France” presented neon tube lighting molecules, say Iodine or Bromine. fi rst electronic fl ash tube, though it had at the Paris Motor Show in December When halogen cools, tungsten is to wait for subsequent developments in 1910. deposited back on the fi lament, in a . Modern cameras use xenon The is basically a low process called the halogen cycle. Now arc tubes as the fl ashbulb. An electric pressure gas discharge lamp, a kind the fi lament can safely reach higher arc is formed through xenon gas with of Cold temperatures, in turn giving brighter the help of a high capacitor. (CCFL). Its glass tube consists of two

The neon lamp

Halogen lamp

40 SCIENCE REPORTER April 2017 The golden yellow colour bathing our roads in the nights comes from the vapour lamp. It is the most effi cient lamp in the world now.

In 1929, Hauser tungsten electrodes. The outer bulb Low-pressure sodium (LPS) lamps Company may be clear or coated with a phosphor have borosilicate glass gas discharge released the to provide for thermal insulation and tube (arc tube) containing solid Vacublitz, protection from radiation. sodium, a small amount of neon, and As the bulb lights up, its resistance gas. When turned on initially the fi rst true drops. So, the current is limited through it emits a dim red/pink light. As the fl ashbulb a ballast or choke. temperature increases, sodium begins vapour lamps are more to vaporize and the lamp turns to pure electrodes fi lled with a mixture of neon energy effi cient than incandescent and yellow. Low-pressure sodium lamps (99.5%) and argon gas. As the voltage most fl uorescent lights, with luminous were invented in 1920 by Arthur H. rises, argon with its low-striking effi cacies of 35 to 65 lumens/watt. Compton, an American physicist who temperature strikes an arc between the They boast a lifetime of 24,000 hours won the Nobel Prize in Physics in electrodes. Now more and more current with high intensity, though they require 1927 for his discovery of the Compton fl ows through the neon gas, ionizing a warm-up of 4–7 minutes to Effect. more atoms. reach full light output. They operate The next development came from Shop displays with brilliant colours at an internal pressure of around 2 to Marcello Pirani who made a sodium- and fancy shapes use helium, xenon, or 18 bar depending on the type, hence the resistant glass in 1931 while working other noble gases along with fl uorescent name high-pressure mercury vapour for in Germany. Further coatings and mercury vapours to make lamp. Their Colour Rendering Index improvements came from Robert L. the required colours. As argon strikes (CRI) is poor with 20 for clear bulb and Coble working at the General Electric the arc, it vaporizes the mercury. The 60 for phosphor coated bulb. Research Lab with his aluminum oxide ultraviolet light emitted by the mercury Though there were rudimentary ceramic (Lucalox) to resist corrosion is absorbed by the phosphor coating, attempts by Charles Wheatstone, John effects of sodium. That paved the which emits light of the desired colour. Thomas Way, and Leo Arons, the fi rst way for the High-pressure sodium That brings us to mercury vapour commercial mercury vapour lamp was (HPS) lamp by William Louden, Kurt lamps that are similar in operation, but developed by in Schmidt, and Elmer Homonnay. with an arc tube made up of quartz and 1901. Hewitt’s light of course was the High-pressure sodium (HPS) lamp precursor of the fl uorescent lamp. has better colour rendering, but with The golden yellow colour bathing a bit of sacrifi ce; it has less effi ciency our roads in the nights comes from than the LPS. Sodium is mixed with the sodium vapor lamp. It is the mercury and xenon to create a more most effi cient lamp in the world now. “white” light. Mercury adds a bit It renders a monochromatic light at a of a blue light to the pure yellow of colour most sensitive to the human the sodium. The arc tube is made eye, the other side of which is poor of aluminum oxide ceramic to resist Mercury vapour Colour Rendering Index (CRI) of 44. corrosion effects of alkalis like sodium. lamp In comparison, an incandescent lamp Ordinary light is produced creates light from to UV with by incandescence due to the heat a small bit in the visible spectrum and produced by the electric resistance CRI of 100. of a conductor (fi lament). On the

41 SCIENCE REPORTER April 2017 Tubelight Sodium vapour lamp

contrary, is produced making these displays possible. They Germer came very close to developing as visible radiant energy due to offer long life with low wattage and the modern fl uorescent lamp. Albert causes other than temperature, such can be manufactured into fl at fl exible W. Hull’s experiments for stronger as , chemil- panels, narrow strings, and other small UV emission from the tube and better uminescence, , shapes. However, they are not useful as electrodes set the stage for the fi nal triboluminescence, and photolumin- general purpose lamps due to their low advancements six years later. escence. output. In 1934, on a visit to Oxford, Most “glow in the dark” toys Really wonderful things go inside England, Arthur H. Compton watched take advantage of . the innocuous looking tubelight, local lamp inventors working with a 2 is produced because although it is often directed as a joke on a ft long tube with yellow-green coloured of chemical reactions, for example not so sharp a person. In 1856, Heinrich phosphors. He wrote to William L. in the fi refl y. Cathodoluminescence Geissler, a German glassblower could Enfi eld at General Electric. Soon is produced when phosphors are produce light by removing almost all Enfi eld led the development of white bombarded by . It is produced of the air from a long glass tube and and reliable fl uorescent lamp. when a substance is exposed to an passing an electrical current through By November, George Inman, electric fi eld without thermal energy it. Known as the Geissler tube, it did Richard Thayer, Eugene Lemmers, generation. not gain popularity until the early 20th and Willard A. Roberts developed the In 1936, Georges Destriau coined century when it became the foundation fi rst true fl uorescent lamp, 10” long the term “Electroluminescence” while of many later lighting , like and ¾” diameter and used zinc silicate working with Marie Curie in her lab. neon lights and low-pressure sodium phosphor (phosphor is the work of In 1907, Captain Henry Joseph Round lamps. Willard A. Roberts). That’s the design observed yellow light when a current Alexandre-Edmond Becquerel fi rst we still use. Around the same time was passed through a silicon carbide used phosphors on the inside of a glass Clifton G. Found and Willard Roberts, detector. Round was an assistant discharge tube in 1859. Thirty years C.A. Nickel and G.R. Fonda worked to Marconi. Electroluminescence was later, in 1891, created for better phosphors [zinc-beryllium mostly a scientifi c curiosity right until an induction lamp. It was not really a silicate (white) and magnesium the invention of thin fi lm deposition “fl uorescent lamp” as we know today tungstate (daylight white)] for better techniques and sandwich of conductors, but his high frequency ballast was a and whiter light. insulators and phosphors. forerunner to high frequency ballasts In 1976, Edward E. Hammer Although they are not classical used in the present fl uorescent tubes. In developed the Compact Fluorescent lamps, electroluminescent lamps do 1896, Thomas Edison made experiments L amp (CFL). GE did not patent hold a niche market for military, with calcium tungstate phosphor it counting on a 28 million dollar medical and industrial equipment where coating but abandoned the project when production facility. The prototype was high brightness, speed, contrast, and his assistant Clarence Dally died after sitting pretty in Hammer’s offi ce and ruggedness are necessary. an exposure to radiation. was later donated to the Smithsonian Old TV sets and computer monitors In 1895, Daniel McFarlan Moore institute. Competing companies copied use electroluminescence. They have an succeeded in lighting a long tube using the design and made hay while the electroluminescent coating made up carbon dioxide and nitrogen to make compact light shined. of phosphors which glow when struck a pink and white light. Though his By 1984, John M. Anderson made by electrons fi red from a cathode in lights adorned department stores in the many improvements in the fl uorescent the back of the tube. Thin fi lm and New York City area, they were short lamp, such as short arc fl uorescent thick fi lm are two technologies used in lived and expensive. In 1926, Edmund lamp, fl uorescent lamp without ballast,

42 SCIENCE REPORTER April 2017 LED bulbs Now, fl uorescent lamps seem to be moving towards the end of their existence as LEDs are increasingly invading domestic lighting. The light output of LEDs has increased exponentially, with a doubling approximately every 36 months since the 1960s. improved electrodes and dimmable Amano were awarded the 2014 Nobel Nick Holonyak Jr. with General fl uorescent lamp. Anderson was a Prize in physics for developing the high Electric, developed the fi rst visible professor at Rensselaer Polytechnic brightness blue LEDs. red LED, reporting this in the journal Institute and employee of General For a moment let us go to back Applied Physics Letters on 1 December Electric with 27 patents related to lamp the early twentieth century when a 1962. In 1972, his student, M. George . feverish pitch was on for the radio. One Craford invented the fi rst yellow LED By now, the 40 W tubelight became of the important circuit elements was and went on improving the brightness the most used lamp in commercial/ a detector. The early detectors were of red and red-orange LEDs to a factor industrial buildings. The tube is usually often made by using a small piece of of ten by 1972. Thomas P. Pearsall fi lled with low-pressure argon and wire onto the crystal surface, called developed a high brightness light- very tiny amounts of mercury. It has “Cat’s Whiskers.” In 1907, Henry emitting diode in 1976, for use with a tungsten electrode on each side. The Joseph Round in Marconi labs noticed fi ber optics in telecommunications. ballast or the choke also limits the yellowish light for the fi rst time when Creating a blue LED was current through the tube. The starter is a potential of 10 volts was applied to considered impossible back then. a bi-metallic neon lamp. As you power carborundum (silicon carbide) crystal. However, Nakamura working at Nichia up, the electrodes heat up, ionize the Although he did not understand the Corporation was convinced that he gas and vaporize mercury. The starter mechanism for the effect, he published could produce it. Founder of Nichia, on and off the power resulting his fi ndings in Electrical World in 1907. Nobuo Ogawa initially supported his in an inductive kick by the choke, a high A Russian engineer named Oleg project, but eventually backed out for voltage running across the tube. Thus, Vladimirovich Losov, son of a Russian fear of too much time and money. an arc is easily struck across the ionized Imperial Army Offi cer investigated Nakamura left Nichia Corporation gas. This continues until fi rm discharge the light emission from zinc oxide and in 1999 and joined the University of is established. Phosphor on the inside silicon carbide crystal rectifi ers. His California, Santa Barbara. Nakamura of the glass tube converts the UV light fi rst paper in Russian in 1927 was titled: has also worked on green LEDs and is emitted into useful visible light. “Luminous carborundum detector and responsible for blue diodes used in This tubelight with magnetic detection crystals.” Sadly, he died of Blu-ray Discs and HD DVDs. ballast or choke can operate at low starvation during the siege of Leningrad The light output of LEDs has frequencies only, and is a major source in the Second World War and all his increased exponentially, with a doubling of energy loss. The starter creates radio work records were destroyed. approximately every 36 months since frequency noise, though a capacitor Kurt Lehovec, Carl Accardo and the 1960s. Similar to Moore’s law, this in it tries to reduce it. Flickering can Edward Jamgochian explained these trend is called Haitz’s law after Dr. be annoying, more so at the end of its fi rst light-emitting diodes in 1951. Rubin Roland Haitz. life. Present electronic ballasts operate Braunstein of the Radio Corporation of In the February 1963 issue of at high frequency with improved America discovered infrared emission Reader’s Digest, Holonyak predicted effi ciency. High frequency operation from gallium arsenide (GaAs) which he that his LEDs would replace the also made it easier to develop the Cold even used in short distance non-radio incandescent light bulb of Thomas Cathode Fluorescent Lamps. , probably the precursor Edison. Will the LEDs also be edged But now, fl uorescent lamps seem of LEDs for optical communication. On out in the future? to be moving towards the end of their 8 August 1962, Biard and Pittman fi led Mr K. Krishna Murty is Director Technical, existence as LEDs are increasingly a patent titled “Semiconductor Radiant Aswartha Condition Monitoring Engineers. invading domestic lighting. Shuji Diode”, the fi rst practical LED based Address: 403 S B Enclave, 11-6-2 Rockdale Nakamura, Isamu Akasaki and Hiroshi on their fi ndings. layout, Maharanipeta, Visakhapatnam-530002; Email: [email protected]

43 SCIENCE REPORTER April 2017

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