Electric Potential: V = IR Explained

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Discussion Overview

The discussion revolves around the relationship between electric potential and Ohm's law, specifically examining how the concepts of electric potential, which varies with distance and charge, relate to the formula V = IR. Participants explore the theoretical underpinnings and implications of these relationships.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants assert that electric potential is inversely proportional to the square of the distance and the product of two charges, questioning how this leads to V = IR.
  • Others argue that Ohm's law represents a material property and is distinct from the potential of a point charge, suggesting that one cannot derive Ohm's law from the laws governing point charges.
  • A participant points out that electric potential actually varies with distance as 1/distance, not 1/distance squared, and emphasizes that this relationship pertains to the source charge.
  • Another participant acknowledges a mistake in their previous statement about the relationship between distance and potential, clarifying that the force between charges follows the inverse square law while potential follows an inverse relationship with distance.
  • One participant suggests reviewing the microscopic Ohm's Law to better understand the issues at hand, noting that when the electric field is uniform, the electric potential changes linearly with distance.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between electric potential and Ohm's law, with no consensus reached on how these concepts interrelate. Some participants clarify their positions and correct earlier statements, but fundamental disagreements remain.

Contextual Notes

Participants highlight the complexity of relating point charge potential to material properties like Ohm's law, indicating that assumptions about uniformity and the nature of the electric field may influence their arguments.

touqra
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Electric potential goes like the inverse of distance squared and the product of the two charges. But I can't see how this can produce V = IR.
 
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touqra said:
Electric potential goes like the inverse of distance squared and the product of the two charges. But I can't see how this can produce V = IR.

The relationship is very remote ! The first you cite is the potential of a *point charge in space*. The second (ohm's law) is the relationship between the motion and the potential distribution of a whole collection of charges within a certain material (which will have its influence on the dynamics).
Ohm's law is a material property (which doesn't always hold, btw), a bit like Hooke's law for the elastic behaviour of materials, while the first law you cited is more like, say, the law of Newtonian gravitation. You cannot derive Hooke's law from Newton's law of gravitation either.
 
touqra said:
Electric potential goes like the inverse of distance squared and the product of the two charges. But I can't see how this can produce V = IR.

The last time I saw, the potential went like one over distance (not squared!) and depended only on the source charge. What you say is true for the force between two point charges, though.
 
neutrino said:
The last time I saw, the potential went like one over distance (not squared!) and depended only on the source charge. What you say is true for the force between two point charges, though.

Ooops. I typed too fast. 1/distance squared for electric force. 1/distance for potential.
 
It might be good to review the microscopic Ohm's Law:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/ohmmic.html
although this presentation doesn't address the relevant issues in the order needed to address the OP.

As a first step, recall that when the electric field is uniform, the electric potential varies linearly with distance.
 
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