Confuse about linear dielectric

  • Thread starter Thread starter athosanian
  • Start date Start date
  • Tags Tags
    Dielectric Linear
AI Thread Summary
In the discussion about linear dielectrics, the relationship between polarization (P) and the electric field (E) is clarified. The textbook states that P is proportional to the total electric field, which includes both the applied external field (E_0) and the depolarization field (E_d). This aligns with the Wikipedia statement that polarization is proportional to the applied external field, but emphasizes that the constant of proportionality can vary based on the material's geometry and position. The key takeaway is that while E is influenced by E_ext, both E and E_ext remain proportional to the charge present. Understanding this relationship helps clarify the confusion surrounding the definitions of E in different contexts.
athosanian
Messages
66
Reaction score
8
hello, I am learning electromagnetism and read the polarization in dielectric. The textbook tell me that in linear dielectric exists a simple relation:
P=\chi*ε0*E
where \chi is the susceptibility, ε0 is the permittivity of vacuum and E is total electric field in the dielectric. It is noted that E is the total field, namely, applied external field E_0 plus depolarization field E_d in the media.
But when I search this topic on the wiki, I find it says polarization is proportional to the applied external field (link below). So I have a confuse about meaning of E, which is right? I hope any help. Thanks.

http://en.wikipedia.org/wiki/Ferroelectricity
 
Physics news on Phys.org
Your textbook is right.
I suppose you refer to the following phrase:
"When most materials are polarized, the polarization induced, P, is almost exactly proportional to the applied external electric field E"
This statement is also true, however, the constant of proportionality will vary with position and depend on the geometry of the sample and external field. Consider for example a charge in front of a half plane of some dielectric. The true electric field lines will break on entering the material while the external field lines radiate unbroken from the charge. Nevertheless both E and E_ext will be proportional to the charge q.
 
Thanks! Drdu, I see. Because E is proportional to E_ext, P is proportional to both E and E_ext.
 
Thread 'Inducing EMF Through a Coil: Understanding Flux'
Thank you for reading my post. I can understand why a change in magnetic flux through a conducting surface would induce an emf, but how does this work when inducing an emf through a coil? How does the flux through the empty space between the wires have an effect on the electrons in the wire itself? In the image below is a coil with a magnetic field going through the space between the wires but not necessarily through the wires themselves. Thank you.
Thread 'Griffith, Electrodynamics, 4th Edition, Example 4.8. (Second part)'
I am reading the Griffith, Electrodynamics book, 4th edition, Example 4.8. I want to understand some issues more correctly. It's a little bit difficult to understand now. > Example 4.8. Suppose the entire region below the plane ##z=0## in Fig. 4.28 is filled with uniform linear dielectric material of susceptibility ##\chi_e##. Calculate the force on a point charge ##q## situated a distance ##d## above the origin. In the page 196, in the first paragraph, the author argues as follows ...
Back
Top