Non-Ohmic Device Study: I-V Graphs and Light Bulb Analysis

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SUMMARY

The forum discussion focuses on the analysis of I-V graphs for resistors and a light bulb, specifically examining the behavior of non-ohmic devices. Participants noted that the light bulb appeared to follow Ohm's Law, producing a straight line on the graph, which contradicts expectations for non-ohmic behavior. This outcome is attributed to the low power source used during the experiment, which prevented the bulb from heating sufficiently to exhibit its true non-ohmic characteristics. Suggestions included using a series resistor to measure voltage across the bulb under different conditions to clarify its resistance behavior.

PREREQUISITES
  • Understanding of Ohm's Law and its implications for resistive and non-resistive devices.
  • Familiarity with I-V graph plotting techniques and data interpretation.
  • Basic knowledge of electrical circuits, including series and parallel configurations.
  • Experience with measuring voltage and current using multimeters.
NEXT STEPS
  • Investigate the characteristics of non-ohmic devices and their I-V curves.
  • Learn about the effects of temperature on resistance in materials, particularly in light bulbs.
  • Explore advanced circuit analysis techniques, including the use of series and parallel resistors.
  • Study the principles of power sources and their impact on circuit behavior.
USEFUL FOR

Students and educators in physics, electrical engineering, and anyone conducting experiments related to circuit behavior and non-ohmic devices.

negat1ve
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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 I am 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>
 
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negat1ve said:
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 I am 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>

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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