
#19
Aug1911, 06:26 AM

Sci Advisor
Thanks
P: 2,132





#20
Aug1911, 06:31 AM

HW Helper
P: 6,189

I suspect you're referring to Maxwell's law that says:
[tex]\textrm{div }\vec E = \frac {\rho} {\epsilon_0}[/tex] The divergence of a spherically symmetric charge is zero everywhere except at the place where the charge actually is. A point charge is a special case, since the charge density would be infinite (actually a Dirac deltafunction). In practice the charge would take in a certain volume. The divergence of the electric field is not zero at the place where the charge density is not zero. 



#21
Aug1911, 08:58 AM

P: 162

So can I go one more step and state that, at the points in space where the charge 'is' the electric field can no longer be defined by the function [itex]\frac{1}{r^2}[/itex][itex]\hat{r}[/itex] ?




#22
Aug1911, 09:44 AM

HW Helper
P: 6,189

Correct.
In the case of a solid sphere with constant charge density within, the electric field is proportional to [itex]r \hat {\boldsymbol r}[/itex] (inside the sphere). 



#23
Aug1911, 10:08 AM

P: 162

thank you, this helped a lot



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