Voltage & Resistance Experiment: Can Resistance Change?

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SUMMARY

The discussion centers on an experiment measuring resistance with varying voltage, challenging the assumption of constant resistance as stated by Ohm's Law. Participants noted that resistance can change due to factors such as temperature variations and the non-linear behavior of materials like diodes and wires at higher currents. The experiment's results suggest that resistance is not always constant, particularly when temperature increases during testing. This highlights the importance of maintaining constant temperature conditions when applying Ohm's Law.

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  • Understanding of Ohm's Law and its limitations
  • Familiarity with I-V (current-voltage) characteristics of materials
  • Knowledge of thermal effects on electrical resistance
  • Basic experimental design and data collection techniques
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  • Research the I-V curve behavior of diodes and how it differs from resistive materials
  • Study the effects of temperature on resistance in conductors and semiconductors
  • Learn about non-linear resistance and its implications in electrical engineering
  • Investigate methods to maintain constant temperature during electrical experiments
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Electrical engineers, physics students, and anyone conducting experiments related to resistance and voltage in conductive materials.

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recently, I did a experiment about insulating coating on a powder.

and I measured resistance with various voltage.

according to Ohm's law, the resistance is constant

however, my sample showed different resistance with difference V.

At every voltage, I checked the currents and the resistance and their multiplies(I*R) show same voltages.

Is it possible that resistance changes?

Please, explain me if anyone can...
 
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Can you post your raw data? V, i, R?
 
It is possible. Take a look a the IV curve for a diode. At different voltages the slope of the curve changes.
 
Even for a simple wire, Ohm's law won't always hold. As you increase the current and voltage, at some point the I-V curve will become non-linear due to the wire heating up.
 
Vagn said:
Even for a simple wire, Ohm's law won't always hold. As you increase the current and voltage, at some point the I-V curve will become non-linear due to the wire heating up.
Ohm's law actually stipulates constant temperature. People confuse Ohm's Law with the simple formula for Resistance (=V/I). There is a distinct difference, of course.
 
The temperature should be constant. I did not clearly understand your experiment, more detail please ?
 

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