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Non ohmic device

  1. Feb 25, 2009 #1
    For a lab yesterday we recorded points to plot the I-V graphs for a few resistors and a light bulb. The light bulb was supposed to show that some that some devices don't obey ohms law but when plotting the graph im cutting more of a straight line then a curve showing that it DOES! Could this be because are voltage and current results came from a low power source that only dimly lit the bulb not giving it a chance to heat up? Or is this an error? How do i report this result>
  2. jcsd
  3. Feb 25, 2009 #2


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    Well for low current the filament won't heat much, so you won't read much difference. But if it is glowing at least it is pretty hot. If you put a resistor in series with the bulb you can measure the voltage across that with the bulb and without the bulb. Then you could measure the bulb alone with very low current of the voltmeter and demonstrate that its heated R is greater than its cold R.
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