Does Resistance Decrease Over Time for Metal Resistors?

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Discussion Overview

The discussion centers around whether the resistance of metal resistors decreases over time with frequent use, particularly in a laboratory context. Participants explore the factors influencing resistance, such as material composition and environmental conditions.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions if the resistance of metal resistors decreases with frequent use and seeks clarification on the context of the question.
  • Another participant mentions that the experimental resistance observed in their lab was consistently lower than expected, prompting their inquiry into whether this is a general rule for metal resistors.
  • A later reply suggests that resistance in metal film resistors generally does not decrease with use, indicating that variations are typically due to initial tolerance and temperature effects.
  • It is noted that damage from overheating or mechanical issues could alter resistance, but this is not a typical outcome of regular use.
  • Concerns are raised about resistors that are out of tolerance, with a recommendation to consult a professor or lab assistant regarding such components.

Areas of Agreement / Disagreement

Participants express differing views on whether resistance decreases with use, with some suggesting it does not typically happen while others share anecdotal evidence of lower experimental resistance. The discussion remains unresolved regarding a general rule for metal resistors.

Contextual Notes

Participants have not specified the type of metal used in the resistors or detailed the experimental conditions, which may influence the discussion. The implications of temperature and tolerance on resistance are acknowledged but not fully explored.

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If a resistor made of a metal is frequently used, will its resistance eventually go down? why?
 
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kahwawashay1 said:
If a resistor made of a metal is frequently used, will its resistance eventually go down? why?

Why do you ask? What is the context of the question? What type of resistor, what composition, what application, etc.?
 
berkeman said:
Why do you ask? What is the context of the question? What type of resistor, what composition, what application, etc.?

As I mentioned, it was a metal resistor. I'm not exactly sure what kind of metal, etc, but the application was that we were doing a lab in school and just applying voltage to the resistor and seeing the resulting current. Our group found that the experimental resistance was consistently lower than the actual range of resistance (considering tolerance values), and I was just wondering if this is a general rule, that resistance goes down with use for metal resistors
 
kahwawashay1 said:
As I mentioned, it was a metal resistor. I'm not exactly sure what kind of metal, etc, but the application was that we were doing a lab in school and just applying voltage to the resistor and seeing the resulting current. Our group found that the experimental resistance was consistently lower than the actual range of resistance (considering tolerance values), and I was just wondering if this is a general rule, that resistance goes down with use for metal resistors

Ah, you mean "metal film" resistors.

In general, no. The resistance will only vary with initial tolerance and with temperature. If the resistor is damaged by overheating or some mechanical problem, then the resistance can change (either up or down).

If you have a resistor in your lab that is out of tolerance, please show it to your professor or lab assistant -- it should be thrown away.
 

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