Potential difference and current

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Discussion Overview

The discussion revolves around the concept of internal resistance in electrical circuits, specifically addressing the relationship between potential difference and current. Participants explore the implications of internal resistance on voltage drops and how this affects circuit behavior, questioning the direct proportionality typically expected between potential difference and current.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion about the internal resistance experiment, noting that potential difference typically increases with current, and questions if there is a missing concept.
  • Another participant explains that the potential difference referred to is the voltage lost due to internal resistance, which decreases the voltage available at the battery terminals.
  • A later reply emphasizes that the relationship described by V=IR holds true, but the context of internal resistance alters the observed potential difference across the load.
  • Some participants acknowledge the counter-intuitive nature of electricity and suggest that understanding comes from applying known principles to unknowns.

Areas of Agreement / Disagreement

Participants do not reach a consensus; while some express understanding, others continue to grapple with the implications of internal resistance on potential difference and current.

Contextual Notes

The discussion highlights the complexity of electrical principles, particularly in relation to internal resistance, and the assumptions that may not be explicitly stated regarding circuit behavior.

Supernova123
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I have trouble understanding the internal resistance experiment in which potential difference decreases as current increases because I thought they are usually directly proportional to each other. Is there any concept that I am missing? I know that the lost voltage will be greater as current increases but doesn't this apply to other experiments as well? Does the experimental setup have anything to do with it?
 
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Supernova123 said:
I have trouble understanding the internal resistance experiment in which potential difference decreases as current increases because I thought they are usually directly proportional to each other. Is there any concept that I am missing? I know that the lost voltage will be greater as current increases but doesn't this apply to other experiments as well? Does the experimental setup have anything to do with it?
Hi and welcome.
Yes V=IR always. The V in question, however, is the V that is dropped / lost as current goes through the internal resistance - leaving fewer volts, delivered to the battery terminals. The volts lost 'inside' plus the volts across the load (the terminals) will add up to the original battery voltage - or emf, as it's called. The rules apply everywhere and if you draw out the circuit you can see what's happening. Otherwise look at this link.
 
I think I understand now. Thanks for your time :)
 
Supernova123 said:
I think I understand now. Thanks for your time :)

Electricity can be confusing as it sometimes seems counter-intuitive. But you can be sure that it always follows the rules and it will not let you down with a 'but not when there's an R in the month' type of exception. The secret is always to work from what you know towards what you don't know. (More difficult to do than you would think in some cases.)
 

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