Potential between two particles

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Homework Help Overview

The discussion revolves around the potential energy between two charged particles, one positively charged (+q) and the other negatively charged (-q). Participants explore the implications of the distance (r) between the charges, particularly as it approaches zero, and the resulting effects on potential and force.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the behavior of potential energy as the distance between the charges decreases, questioning the implications of r approaching zero. There are considerations about the physical size of the charges and how that affects the potential and force between them.

Discussion Status

The conversation is ongoing, with some participants suggesting that the potential becomes infinite as r approaches zero, while others counter that the physical size of the charges prevents this scenario. There is no explicit consensus, but various interpretations of the problem are being explored.

Contextual Notes

There is a notable assumption regarding the size of the particles and the implications of ignoring physical realities in the discussion. Participants are grappling with the theoretical limits of the model being discussed.

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If we have two particles +q and -q. then the potential between them is <0 and therefore they will attract to each other. but what will happen when r is almost 0 (since we have r in the denominator)?
 
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The force of attraction gets larger as the distance diminishes.
The distance can never be zero because charges have size and the distance is measured from center to center. When the charges touch, some or all will cancel.
 


We cannot make the separation 0 between the two charges, however if you place a third particle very far away the force on the test particle from the difference in the charges will approximately cancel out.
 


I understand that, but let's say that the particles don't have "size", then in r=0 the potential will be infinity. the force of the attraction will cause them to get closer until r=0 , so how the potential can grow to infinty?
 


It can't because the particles do have size! You can't say "let's ignore physics" and then ask what physics says!
 

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