Resistance and Electric Potential

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Discussion Overview

The discussion revolves around the concepts of resistance and electric potential in electrical circuits, particularly focusing on how potential is lost across resistors and the behavior of charges within conductors. Participants explore theoretical and conceptual aspects of these topics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about how potential is lost when power is dissipated through a resistor, questioning the relationship between potential, charge, and distance.
  • Another participant explains that potential is uniform in a conductor due to the free movement of charges, which minimizes potential differences.
  • There is a discussion about the role of a battery or power supply in maintaining constant potential across a circuit, even in the absence of a resistor.
  • Concerns are raised about the implications of having no resistor, emphasizing that even wires have some resistance that affects current flow.
  • A participant inquires about the change in potential across individual resistors in series, questioning what causes this change if resistors do not affect charge distribution.
  • Responses suggest that resistors do impact charge distribution by creating local electric fields that resist current, leading to lower potential on the other side of the resistor.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the nuances of how potential is lost across resistors and the implications of charge distribution within circuits. Multiple perspectives on these concepts remain present throughout the discussion.

Contextual Notes

Some statements rely on assumptions about ideal conductors and resistors, and the discussion does not resolve the complexities of potential changes in circuits with multiple resistors.

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This is probably a simple concept but I'm struggling a little bit understanding it. When power is dissipated through a resistor, how is potential actually lost? I understand energy is converted into heat and other forms, but isn't potential just defined as a function inversely proportional to distance and proportional to charge (i.e. q/r)? I'm sure I'm misinterpreting the different terms, though, because potential is at approximately the same level at all points on a conductor (assuming negligible resistance), so it can't simply be a function of distance.
 
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Potential is a function of distance from charge, but each point in the conductor is roughly equally far apart from a similar amount of charges. This is what makes it a conductor. The charges in a conductor are free to move around. So if at one point there is higher potential than another, this will cause charges to move. They will move until they minimize their potential and at this point the potential will be uniform throughout the conductor. (the charges have naturally arranged themselves such that they are roughly equal distance from each other)
 
ModusPwnd said:
Potential is a function of distance from charge, but each point in the conductor is roughly equally far apart from a similar amount of charges. This is what makes it a conductor. The charges in a conductor are free to move around. So if at one point there is higher potential than another, this will cause charges to move. They will move until they minimize their potential and at this point the potential will be uniform throughout the conductor. (the charges have naturally arranged themselves such that they are roughly equal distance from each other)

Oh I see. That makes a lot of sense. So if there was no resistor in a circuit, would the potential just keep building up?
 
The current would build up. The battery or power supply is designed to put out a constant voltage, which is potential. So the potential across your entire circuit is constant.

For the situation with no resistor you should remember that nothing is a "perfect" conductor. The wire has a small amount of resistance. If you have no resistor in the circuit then you can't really neglect the wire's resistance, because that's all you have. With no resistor you have the minute resistance of the wire which leads to very large current (via ohm's law).
 
ModusPwnd said:
The current would build up. The battery or power supply is designed to put out a constant voltage, which is potential. So the potential across your entire circuit is constant.

For the situation with no battery you should remember that nothing is a "perfect" conductor. The wire has a small amount of resistance. If you have no resistor in the circuit then you can't really neglect the wire's resistance, because that's all you have. With no resistor you have the minute resistance of the wire which leads to very large current (via ohm's law).

Okay. One last thing regarding this... How does this work regarding multiple resistors, for example two in a series? That is, what causes the change in potential between the terminals of an individual resistor, when the resistors themselves do not affect the charge distribution? I understand a battery creates an emf by moving particles, but what changes the potential within a circuit?
 
Good question. I think resistors do affect the charge distribution. Or I should say, in a resistor the charges are not as free to move around. Because they don't move around as easily they can put up a local electric field that "resists" the current entering the resistor. Then you have a lower potential on the other side, since the other side is connected to the battery.

Im sure this can be explained better by someone more knowledgeable...
 
ModusPwnd said:
Good question. I think resistors do affect the charge distribution. Or I should say, in a resistor the charges are not as free to move around. Because they don't move around as easily they can put up a local electric field that "resists" the current entering the resistor. Then you have a lower potential on the other side, since the other side is connected to the battery.

Im sure this can be explained better by someone more knowledgeable...

Okay thank you for your help.
 

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