Question about this situation with two point charges +Q and -Q

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Discussion Overview

The discussion revolves around the net electric force experienced by a charge +Q when placed near another charge -Q, particularly when a neutral metal rod is introduced between them. Participants explore the implications of the rod's presence on the force exerted on +Q, considering both theoretical and practical aspects of electric fields and charge distribution.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions whether the net electric force on +Q would be the same with and without the neutral rod, suggesting that the problem may have nuances that complicate the answer.
  • Another participant suggests using Coulomb's law and modifying it to account for the dielectric constant introduced by the metal rod.
  • A participant expresses uncertainty about how the charge distribution in the neutral rod would affect the forces, proposing that the distribution may not be uniform due to the influence of the external charges.
  • One participant describes how the presence of the metal rod would lead to charge separation, resulting in one end of the rod becoming positively charged and the other negatively charged, which could affect the net force on +Q.
  • A later reply raises a question about whether the metal rod is in contact with the charges, indicating that this could influence the situation.
  • Another participant speculates on the thickness of the rod and its effect on the electric field, suggesting that a thicker rod might reduce the effective distance between the charges.

Areas of Agreement / Disagreement

Participants express differing views on the impact of the neutral metal rod on the net electric force experienced by +Q. There is no consensus on whether the force would be the same in both scenarios, and multiple competing perspectives on the role of charge distribution and field effects are presented.

Contextual Notes

Participants note the lack of information regarding the charge distribution on the neutral rod and the potential implications of this uncertainty on the overall analysis. The discussion also highlights the complexity of electric fields in the presence of conductors, which may not be fully resolved.

Theelectricchild
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Would the magnitude of the net electric force on a charge +Q in a case where there is another charge -Q a distance x away from +Q be equal to the force on +Q by -Q in a case where there is a neutral metal rod between them? (and same distance x away from each other)

I would be inclined to say that there would be NO difference, that is, the net force would be equal in both cases, but the question seems deceptively easy--- can i confirm this, and are there special cases when this is not true?

I should note that the problem does not state how the charge is distributed on the neutral rod, that is, if the positive charges are on one side (IE left has the positive and the negative charges are on the right side--- and having an equal amount would make the rod neutral)--- I know metal is a conductor--- would that mean that the charge is distributed uniformly even in a neutral state?

I am quite new to electricity in general so please ask for clarification if something didnt make sense!

Thanks for your help!
 
Last edited:
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use coulomb's law

use coulomb's law and just replace the dielectric constant!
 
Hi thanks for your response, but could you please explain that a bit? Replace it with what?

Heres my reasoning now that I've thought it over a bit longer:

Wont the negative charge that is in the metal rod wish to "come closer" to the positve Q charge while the positive charge in the metal rod comes closer to the -Q charge? IE the distribution of charge throughout the metal rod is not uniform--- and thus would play a role in showing that the force between Q and -Q would be greater in this case?

Thanks for your help.
 
I just constantly have a gloomy cloud over my head :(
 
oh well thanks for your help anyway
 
As I see it, if you have 1 plus charge and 1 minus charge, you'll have an electric field between them. If you place a metal rod between them, then the plus charges of the rod will be pulled towards the - charge and the negative charges of the rod will go the opposite way. You'll have one end of the rod with + charge and the other with - charges. That will affect the net force on the Q charge

Greetings
Javier
 
Does the metal rod touch the charges?
 
I suspect that the rod charges separate as you say ( meaning electrons will accumualte at one side ), if the rod was a plate ( easiesr to think about) then if it was thin there would be no net field disturbance , but if it was thick then it reduces the effective q1/q2 distance -- field lines must be perpendicular to the plate.
You could graph that by splitting the field q1/q2 down the middle and moving thm apart.Ray
 

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