Voltage and resistance

  • Thread starter sunwoo lee
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  • #1
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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Answers and Replies

  • #2
Bystander
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Can you post your raw data? V, i, R?
 
  • #3
CWatters
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It is possible. Take a look a the IV curve for a diode. At different voltages the slope of the curve changes.
 
  • #4
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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.
 
  • #5
sophiecentaur
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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.
 
  • #6
The temperature should be constant. I did not clearly understand your experiment, more detail please ?
 

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