Skip to main content
11 events
when toggle format what by license comment
Aug 26, 2015 at 22:07 comment added Brian Moths @JohnM You got it backwards here and in a comment to your answer. $D$ gives you $\rho_f$ and $E$ of course gives you the total $\rho$. Since $\rho_f$ is zero, $\nabla \cdot D$ must be zero, but since we are linear, $\nabla \cdot P$ must be zero as well.
S Aug 26, 2015 at 20:28 history edited Sepideh Abadpour CC BY-SA 3.0
fixed a typo and added a dielectric tag
S Aug 26, 2015 at 20:28 history suggested John M CC BY-SA 3.0
fixed a typo and added a dielectric tag
Aug 26, 2015 at 20:23 review Suggested edits
S Aug 26, 2015 at 20:28
Aug 26, 2015 at 20:08 comment added John M $\nabla \cdot {\boldsymbol P} = \rho_b$ is for bound volume charges. Free charges are slightly different -- total field responds to $\nabla \cdot {\boldsymbol E} = \rho_f$
Aug 26, 2015 at 20:06 comment added Brian Moths It is not clear to me that the absence of source charges implies that $\vec{M} = \vec{P} = \vec{0}$. In fact, I would have thought that the electromagnetic wave would disturb the medium and cause a polarization to form. Similarly, a magnetic field would induce a magnetization. However, with no free sources I would expect $\vec{\nabla} \cdot \vec{P} = \vec{0}$.
Aug 26, 2015 at 20:01 answer added John M timeline score: 3
Aug 26, 2015 at 19:14 history edited Sepideh Abadpour CC BY-SA 3.0
added 105 characters in body
Aug 26, 2015 at 19:06 history edited Sepideh Abadpour CC BY-SA 3.0
added 436 characters in body; edited tags
Aug 26, 2015 at 18:55 history edited Sepideh Abadpour CC BY-SA 3.0
added 436 characters in body; edited tags
Aug 26, 2015 at 18:24 history asked Sepideh Abadpour CC BY-SA 3.0