Integral of product of infintesimal volume

Click For Summary

Discussion Overview

The discussion revolves around the calculation of energy in charge configurations, particularly in the context of the integral of the product of infinitesimal volume with the square of the electric field. Participants explore the implications of this formula, its application to different charge distributions, and the concept of energy associated with point charges and dipoles.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions the interpretation of the energy calculation in Griffiths' book, noting a potential contradiction regarding the infinite energy associated with the fabrication of point charges versus the definite values obtained for spherical or cylindrical charge configurations.
  • Another participant states that the energy stored in a charge configuration represents the work needed to assemble it, suggesting that point charges are merely models and that spherical charge distributions behave like point charges externally.
  • A participant raises a query about the energy calculation for equal and opposite charges, pointing out a discrepancy between the always positive result from the integral formula and the negative value obtained from the formula for interaction energy between charges.
  • References to energy stored in an electric dipole and the work involved in positioning charges are provided, emphasizing that the work done does not depend on the method of charge assembly, as it involves conservative forces.

Areas of Agreement / Disagreement

Participants express differing views on the implications of energy calculations in charge configurations, particularly regarding the treatment of point charges and the nature of energy in systems with equal and opposite charges. The discussion remains unresolved with multiple competing perspectives on these issues.

Contextual Notes

Participants highlight potential limitations in understanding the implications of energy calculations, particularly concerning the assumptions about charge fabrication and the nature of electric fields in different configurations.

vijaypandey93
Messages
20
Reaction score
0
I'm following the book ''introduction to electrodynamics by D.J. Griffiths''. As he has written that the formula ''integral of product of infintesimal volume with the square of electric field'' gives us the energy contained in a charge configuration that is always positive because we're encountering square.He has justified it by saying that it even considers the fabrication of charges and as we know the fabrication of point charge involves infinite energy.But why do i get a definite value when i calculate the energy of a charge configuration like spherical or cylindrical,rather if I'm following his argument correctly then in spherical,this formula should take into account of fabrication of all the charges and that's certainly infinite.what's that in his argument that I'm not getting?Please help!
 
Physics news on Phys.org
okay but what'd we get if we calculate the energy due to equal and opposite charges?should it be positive or negative?according to the formula statrd above,it'll always be positive.and using the formula [k(q1)(q2)]/r,it's negative.can you please justify how?
 
Last edited by a moderator:

Similar threads

  • · Replies 8 ·
Replies
8
Views
2K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 3 ·
Replies
3
Views
942
  • · Replies 7 ·
Replies
7
Views
2K
  • · Replies 12 ·
Replies
12
Views
3K
Replies
2
Views
2K
  • · Replies 3 ·
Replies
3
Views
8K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 4 ·
Replies
4
Views
2K