Volume charge density w/o surface charge density

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SUMMARY

The discussion centers on the concept of electric fields in Griffiths' electrodynamics, specifically addressing the relationship between electric fields inside and outside a uniformly charged volume. The equation E_{out} - E_{in} = \frac{\sigma_{free}}{\epsilon_0} is referenced, with specific electric field expressions given for a uniform circular charge density: \vec{E_{in}} = \frac{\rho r}{3\epsilon_0}\hat{r} and \vec{E_{out}} = \frac{\rho R^3}{3\epsilon_0 r^2}\hat{r}. The participant resolves their confusion regarding the necessity of surface charge density when a volume charge density exists, clarifying that the normal to the electric field is in opposite directions when using a 'pillbox' method.

PREREQUISITES
  • Understanding of Griffiths' electrodynamics
  • Familiarity with electric field concepts
  • Knowledge of charge density and its implications
  • Experience with the 'pillbox' method in electrostatics
NEXT STEPS
  • Study Griffiths' Electrodynamics, focusing on Chapter 2 regarding electric fields
  • Learn about the implications of surface charge density in electrostatics
  • Explore the 'pillbox' method for analyzing electric fields at boundaries
  • Investigate the relationship between volume charge density and electric field continuity
USEFUL FOR

Students and professionals in physics, particularly those studying electrodynamics, as well as educators seeking to clarify concepts related to electric fields and charge densities.

vikasagartha
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Im confused by a concept i have run across in Griffiths electrodynamics.

[itex]E_{out} - E_{in} = \frac{\sigma_{free}}{\epsilon_0}[/itex]

However, in the case of a uniform, circular charge density,
[itex]\vec{E_{in}} = \frac{\rho r}{3\epsilon_0}\hat{r}[/itex]
[itex]\vec{E_{out}} = \frac{\rho R^3}{3\epsilon_0 r^2}\hat{r}[/itex]

But this electric field is continuous @ r=R. If a volume has a charge density, doesn't it have to have some sort of a surface charge? How can there be no surface charge?
 
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Silly question. Realized my mistake. Sorry. I forgot that the normal to the electric field is in opposite directions when drawing a 'pillbox.' So sorry.

Answered my own question.
 
Last edited:

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