electrical characteristics of tungsten

Discussion in 'General Electronics Chat' started by paul, Jan 28, 2007.

  1. paul

    Thread Starter New Member

    Jan 28, 2007
    1
    0
    I am carring out an experiment using a 12 volt 5wtt bulb. When I apply 6,9 and 12 volts to the bulb it draws a current of 0.56, 0.697 and 0.825 amps respectively. To me it seems as though the filament resistance in the lamp is nonlinear.

    Could you explain why this is so. That is if my assupmtions are correct.

    Thanks
     
  2. Distort10n

    Active Member

    Dec 25, 2006
    429
    1
    I am not a materials engineer so that could very well be. What is your setup and how are you measuring?
     
  3. mrmeval

    Distinguished Member

    Jun 30, 2006
    833
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  4. Gadget

    Distinguished Member

    Jan 10, 2006
    613
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    The hotter the filiment is, the higher the resistance. It's a well known property of bulbs and heater elements and can be usefull.
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    It is this non-linearity which allows ordinary light bulbs to be used as current regulators in simple electroplating and anodizing rigs. I've seen one EDM that uses the same principle.
     
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