Problem with understanding polarization

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The discussion centers on the contradiction arising from the equations governing polarization and electric fields in linear dielectrics. It highlights that a linearly polarized dielectric ball generates an internal electric field, but also presents a conflicting relationship between polarization and electric field strength. The key point is that if a dielectric is polarized without an external field, it cannot be considered linear. This indicates that the assumptions made about the dielectric's behavior under polarization may not hold true without an applied field. Therefore, the conclusion is that a linear dielectric cannot maintain polarization independently of an external electric field.
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Suppose we have a ball made of linear dielectric with permittivity \epsilon, with some initial homogenous polarization \vec{P} aligned with z axis. Then we know that inside the ball the polarization generates an electric field \vec{E}=\frac{-1}{3\epsilon_{0}}\vec{P} (standard calculation). But we also know that in a linear dielectric we have the relation \vec{P}=(\epsilon - \epsilon_{0})\vec{E}, and these two equations lead to contradiction since we have \vec{E}=\frac{-1}{3\epsilon_{0}}\vec{P} = \frac{-1}{3\epsilon_{0}}(\epsilon - \epsilon_{0})\vec{E}. Does it mean that a linear dielectric can't be polarized this way without an external field?
 
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neworder1 said:
Suppose we have a ball made of linear dielectric with permittivity \epsilon, with some initial homogenous polarization \vec{P} aligned with z axis. Then we know that inside the ball the polarization generates an electric field \vec{E}=\frac{-1}{3\epsilon_{0}}\vec{P} (standard calculation). But we also know that in a linear dielectric we have the relation \vec{P}=(\epsilon - \epsilon_{0})\vec{E}, and these two equations lead to contradiction since we have \vec{E}=\frac{-1}{3\epsilon_{0}}\vec{P} = \frac{-1}{3\epsilon_{0}}(\epsilon - \epsilon_{0})\vec{E}. Does it mean that a linear dielectric can't be polarized this way without an external field?

Yeah, of course! If there is no field, and the object is polarized... it's not a linear material.
 
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