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Electric Lighting - 1 ELECTRIC LIGHTING A. PREPARATION 1. Introduction 2. Irradiance 3. Black Bodies and Lasers 4. Generalized Luminous Flux and Related Quantities 5. Photometric and Quantum Measures 6. Flicker and Color Temperature 7. Desirable Illumination Levels 8. Principal Lamp Types a) Introduction b) Incandescent c) Glow Discharge d) Arc Discharge 9. The Ordinary Incandescent Lamp 10. The Ordinary Fluorescent Lamp 11. The Low-Pressure Sodium-Vapor Lamp 12. Considerations of Waveform and Power 13. The Pipkin Page 14. Glossary 15. References B. EXPERIMENT 1. Equipment List 2. Flicker 3. The Photometer and Its Use 4. The 60-W Incandescent Lamp 5. The 40-W Rapid-Start Fluorescent Lamp 6. The 55-W -Low-Pressure Sodium-Vapor Lamp C. REPORTElectric Lighting - 2Electric Lighting - 3Electric Lighting - 4Electric Lighting - 5Electric Lighting - 6Electric Lighting - 7Electric Lighting - 8Electric Lighting - 9Electric Lighting - 10Electric Lighting - 11Electric Lighting - 12Electric Lighting - 13Electric Lighting - 14Electric Lighting - 15Electric Lighting - 16Electric Lighting - 17Electric Lighting - 18Electric Lighting - 19Electric Lighting - 20Electric Lighting - 21Electric Lighting - 22Electric Lighting - 23Electric Lighting - 24Electric Lighting - 25Electric Lighting - 26Electric Lighting - 27Electric Lighting - 28Electric Lighting - 29Electric Lighting - 30Electric Lighting - 31Electric Lighting - 32Electric Lighting - 33Electric Lighting - 34Electric Lighting - 35Electric Lighting - 36 The PPPiiipppkkkiiinnn PPPaaagggeeesss The legacy of Marvin Pipkin looms large in the history of electric lighting. But only for his luminous technical achievements. About Pipkin the man we know virtually nothing§. In the early years of incandescent lamps, the bulb was of clear glass and the apparent source of light the filament itself. This caused severe glare and eye-strain and led to the development of lampshades which, in addition to reducing glare by diffusing the light, also reduced the reduced the intensity of illumination. Then, about 1925, Marvin Pipkin of General Electric discovered the secret of inside-frosting light bulbs. For many years people had recognized the utility of frosting since it reduced the brilliance of the filament by a factor of roughly a hundred. And originally the frosting was achieved either by acid etching or spraying a mineral paint onto the exterior surface: both methods tended to absorb rather more light than one would wish; and the acid etched surface had a tendency to collect dirt and inhibit the removal thereof. However, inside etching weakened the bulb and enhance breakage (Howell and Schroeder, 1927). The problem was that the acid etch cut tiny sharp crevices in the glass, from which larger crevices were wont to grow when pressure was applied to the external surface (either by lowering the pressure inside the bulb or by incautious handling). Pipkin’s brilliant solution was to apply a second etch which rounded out the bottoms of the crevices and greatly inhibited stress-cracking of the bulb. The resultant bulb caused the apparent source of the light to expand from the filament to a sphere of much reduced luminance inside the bulb; the resulting loss in efficacy was about 2%, roughly three-fold less than with outside-frosting. With this advance, GE introduced the familiar “standard” bulb shape in the familiar 15 , 25 , 40 , 50 , 60 , 100 sequence. Not content to rest on his laurels, Pipkin went on in 1949 to invent the Q-coat process in which the inside of the lamp is “smoked” with minute particles of pure silica. This resulted in only a slight loss of efficacy (~2%) while making the apparent source of light the surface of the bulb itself. This breakthrough is familiar to you as the Soft White light bulb. Let us now praise famous men, and our fathers that begat us. The Lord hath wrought great glory by them through his great power from the beginning ... Leaders of the people by their counsels, and by their knowledge of learning meet for the people, wise and eloquent are their instructions ... All these were honoured in their generations, and were the glory of their times. There be of them, that have left a name behind them, that their praises might be reported. And some there be, which have no memorial; who are perished, as though they had never been; and are become as though they had never been born; and their children after them. But these were merciful men, whose righteousness hath not been forgotten ... and their glory shall not be blotted out. Ecclesiasticus 44: 1-13 § If you can discover items of interest for the Pipkin Pages, please submit them to the instructor together with complete bibliographical details.Electric Lighting - 37 14. Glossary and Manufacturers’ Data Sheets There are many specialized terms associated with lighting, as can be seen by examining the following glossary taken from a recent Graybar catalogue. On several following pages you will find interesting illustrations of items of interest and a Data Sheet on the photometric sensor. 15. References Cited & Recent Monographs Worth Examining. Anonymous. Fluorescent Lamps. Cleveland, General Electric (undated). (GE bulletin TP-111R] Anonymous. Incandescent Lamps. Cleveland, General Electric (1980). [GE bulletin TP-11OR11 Barrows, W.E. Light, Photometry, and Illuminating Engineering (3rd edn.). New York, McGraw-Hill (1951). Elenbaas, W. Light Sources. New York, Crane, Russak & Company (1972). Gaster, L. and Dow. J.S. Modern Illuminants and Illuminating Engineering. London, Whittaker (1915). Howell, J.W. History of the Incandescent Lamp. Schenectady, NY, Maqua Company (1927). Nuckolls, J.L. Interior Lighting for Environmental Designers. New York, John Wiley & Sons (1976). Rupert, C.S. and Latarjet, R. Toward a nomenclature and dosimetric scheme applicable to all radiations. Photochem. Photobiol. 28, 3-5 (1978). Sears, F.W. Optics (3rd edn.). Cambridge, Addison-Wesley (1949). Shibles, R. Committee report: Terminology pertaining to photosynthesis. Crop Sci. 16, 437-439 (1976). Wright, W.D. The Measurement of Colour (4th edn.). New York, Van Nostrand Reinhold (1969). MONOGRAPHS Cayless, M. A. and Marsden, A. M. Lamps and Lighting. Baltimore ,Edward Arnold


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WUSTL ESE 435 - ELECTRIC LIGHTING

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