Can There Be a Center of Charge Like Center of Mass?

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Discussion Overview

The discussion revolves around the concept of a "center of charge" and its analogy to the "center of mass." Participants explore whether it is valid to represent a distribution of charge as a single point for the purpose of applying Coulomb's law and calculating electric fields, particularly in systems with multiple point charges.

Discussion Character

  • Exploratory
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant questions if a center of charge can be defined similarly to a center of mass, suggesting that charge could be concentrated at a point for calculations.
  • Another participant proposes that if the entire force is concentrated at one point, it could simplify analysis.
  • A different participant raises a specific scenario involving three unequal point charges at the vertices of an equilateral triangle, asking if the total charge can be treated as concentrated at a single point for electric field calculations and if a general expression for the center of charge can be derived.
  • In response, a participant argues that a center of charge is not generally applicable, citing an example of a system with a positive and negative charge that has no net charge but still produces an electric field, emphasizing the importance of the dipole term in charge-neutral systems.
  • Another participant expresses appreciation for the explanation provided regarding the dipole field and its implications.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the validity of defining a center of charge. There are competing views on whether charge distributions can be simplified to a point charge for calculations, particularly in systems with neutral charges.

Contextual Notes

The discussion highlights the complexity of charge distributions and their effects on electric fields, particularly in cases where the total charge is zero, which complicates the analogy to the center of mass.

gandharva_23
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like centre of mass can there be a concept of centre of charge . To apply Newtons laws of motion one can assume a point on the body to represent the whole body and assume the entire mass to be concentrated at that point . to apply coulomb's law can i assume all the charge of the body to be concentrated at a given point ?
 
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Assume that the entire force is concentrated in one point of the body, at the center.
 
you probably dint get the question or i m unable to understand what u r trying to say .if i have 3 unequal point charges located on the vertices of an equilateral triangle then can i assume the whole charge to be concentrated at one point to represent the whole system ? i.e one can assume the entire charge to be concentrated at that point for the purpose of calculating the electric field intensity ? can we derive a general expression for coordinates of center of charge like center of mass ?
 
Hi ghandharva, if I understand your question correctly then the answer in general is no. Consider the following the situation. I have a positive and a negative charge fixed at either end of an uncharged rod which lies on the x axis. This system has no net charge but it still has a nonzero electric field. Furthermore, a positive charge placed further down the x-axis will exert a non-zero force on the system. As Astronuc talked about in your other thread on this topic, there is a sense in which only the total charge is relevant. If the total charge of a system is nonzero, then far away from the system the electric field of the system will look like the field of a single point charge whose magnitude is the sum of all the charges in the system. This is called the monopole part of the field, but in our case this term is zero since the total charge is zero. The result is that far away from the system the electric field looks like a dipole field which falls off as [tex]1/r^3[/tex] with distance unlike the [tex]1/r^2[/tex] dependence of the monopole term. Because many interesting systems are charge neutral, the dipole term is very important for many real world applications. See here for more: http://hyperphysics.phy-astr.gsu.edu/Hbase/electric/dipole.html

Hope this helps.
 
the explanation was pretty useful ... thanks a lot .
 

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