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Finding the temperature of light bulb filament?

  1. Jan 7, 2008 #1
    So for my physics independent study project. I am studying the resistance vs. temperature in non-ohmic material. I passed different currents through the light bulb and took the surface temperature with a thermocouple. How can I find the temperature of filament using the surface temperature measurement? My teacher seemed to think that would be easy, but I can't find it anywhere. Can anyone please help me? I do not want to start my project all over again and I don't know how I would even measure the temperature of the filament seeing as my school does not own a optical pyrometer.

  2. jcsd
  3. Jan 7, 2008 #2


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    The filament temperature will be hard to get given only bulb surface temperature measurements. However, the color of the filament is a direct indication of the temperature. Devices called optical pyrometers are used to take this type of measurement. Do some research in that direction, perhaps you can find color/temperature charts which will be useful.
  4. Jan 7, 2008 #3
    The intensity of the radiation from a blackbody is proportional to the forth power of the BB temperature. You can determine relative temperatures by a standard photovoltaic cell's measurements of the emitted electromagnetic energy.

    Mine is a simplification of the process you seek. Integral knows better what to do in practice, however.
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