Preferences help
enabled [disable] Abstract
Number of results
2017 | 15 | 86-97
Article title

Heating-times of tungsten filament incandescent lamps

Title variants
Languages of publication
The electricity provides power to incandescent lamps to heat the filament hot enough so that it provides light for illumination. The time taken to achieve a state of full brilliance after being turned on is so fast that it may be presumed to be adiabatic and the corresponding time may be called adiabatic heating time. In view of the fact that in actual practice simultaneously the black-body radiation cools the filament, the General Electric in its bulletin provides a better time scale describing heating and cooling of filament. These are average times required for the filament to warm up to 90 per cent light output after the circuit is closed, or to cool down to 10 per cent after the circuit is opened, respectively. The exercise of estimating luminous flux and heating-times for typical 10, 100, 500 and 1000 W lamps have been undertaken for the first time for the benefit of students. This problem involves three disciplines electricity, optics and heat. The electricity provides power to heat the filament quickly, followed by optics which helps us in determining the light output and lastly the discipline heat provides method to solve the heat equation for estimating these times. It is shown that the supposition of linear configurations for the filaments neither matches luminous flux nor the heating-times and both fall short. HS Leff suggestion of introducing a shadow factor which reduces the exposed surface area, as it so happens in the coiled filaments, successfully explained the measured observations.
Physical description
  • [1] V. J. Menon and D. C. Agrawal. Switching time of a 100 watt bulb, Phys. Educ. 34, 34-36, 1999
  • [2] Incandescent Lamps, Pamphlet TP-110R2 (Nela Park, OH: General Electric Company, 1984) pp. 35, 24
  • [3] H. S. Leff Illuminating physics with light bulbs, Phys. Teach 28, 30-35, 1990
  • [4] H. A. Jones and Irving Langmuir The characteristics of tungsten filaments as functions of temperature: Part II, Gen. Electr. Rev. 30, 354-361, 1927
  • [5] M. R. Vukcevich The Science of Incandescence, (Advanced Technology Department, GE Lighting, Nela Park, Cleveland, 1992), Chapter 9.
  • [6] D. C. Agrawal, H. S. Leff and V. J. Menon Efficiency and efficacy of incandescent lamps, Am. J. Phys. 64, 649- 654, 1996
  • [7] D. C. Agrawal Moon, Super-Moon, Planets of the Solar System and Star Vega: Brightness and Size, J. Phys. Astron. 5, 1-20, 2017
  • [8] R. D. Larrabee The spectral emissivity and optical properties of tungsten, Technical Report 328, (Research Laboratory of Electronics, MIT, Cambridge, Mass, 1957)
  • [9] W. H. Stephen and Chun T. Wang Tungsten Sources, Metallurgy, Properties and Applications, Plenum, New York, 1979, chapter 6
  • [10] W. S. Wagner Temperature and color of incandescent lamps, Phys. Teach 29, 176-177, 1991
  • [11] V. J. Menon and D. C. Agrawal Lifetimes of incandescent bulbs, Phys. Teach 41, 100-101, 2003
  • [12] V. J. Menon and D. C. Agrawal A theory for the mortality curve of filament lamps, Journal Mater. Engg. Perf. 16, 1-6, 2007
  • [13] D. C. Agrawal and V. J. Menon Light bulb exponent-rules for the classroom, IEEE Trans. Educ. 43, 262-265, 2000
  • [14] H. A. Jones and Irving Langmuir The characteristics of tungsten filaments as functions of temperature: Part I, Gen. Electr. Rev. 30, 310-319, 1927
  • [15] D. C. Agrawal, Cooling-times of tungsten filament lamps, World News of Natural Sciences, 13, 52-62 (2017)
Document Type
Publication order reference
YADDA identifier
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.