Div D, div E. What rho is it. (electrostatics)

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The discussion clarifies the relationship between the electric displacement field (D) and the electric field (E) in the context of electrostatics, particularly within isotropic, linear, and homogeneous dielectrics. It emphasizes that the divergence of D relates to free charge density (rho), while the divergence of E involves both free and bound charges. The participants correct a misunderstanding regarding the presence of bound charges, concluding that bound charges do exist, as indicated by the divergence of polarization (P) not being zero. The correct formulation involves using ε0 in the equations, which aligns with established physics principles. Overall, the conversation highlights the nuances of charge density in dielectric materials.
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I know that the D field has to do with free charges. So when we write Maxwell's equation ##\vec \nabla \cdot \vec D = \rho## we mean rho as the free charge density which does not include the bound charges also known as polarized charges.
I know that the E field has to do with both the free charges and bound charges. However if the region I'm concerned about is an isotropic, linear and homogeneous dielectric then ##\vec D = \varepsilon \vec E## and thus ##\vec \nabla \cdot \vec E = \frac{\rho }{\varepsilon }##.
Where rho in this case is also the free charge density.
But I'd have thought that ##\vec \nabla \cdot \vec E = \frac{\rho _\text{free}+ \rho _{\text{bound}}}{\varepsilon }##. I'm guessing this equation is not false, but it's just that the nature of the dielectric makes that ##\vec \nabla \cdot \vec P=0## (which is also worth ##-\rho _\text{bound}##). So that means that in an isotropic, linear and homogeneous dielectric there are no bound charges?
 
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atyy said:
If I understand your notation, I think it is wrong. One should have ε0 in the RHS denominator, like Eq 2 of http://www.pa.msu.edu/~duxbury/courses/phy481/Fall2009/Lecture27.pdf.


Yes you are right, I've just rederived it via ##\vec D = \varepsilon _0 \vec E - \vec P##, taking the divergence.
Therefore I'm left to see that ##\frac{\rho _\text{free}+ \rho _{\text{bound}}}{\varepsilon _0 } = \frac{\rho _\text{free}}{\varepsilon}##.
I can already answer a question in my first post, namely "So that means that in an isotropic, linear and homogeneous dielectric there are no bound charges?", the answer is no, because div P is not worth 0.
 
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