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conduction, polarization & magnetization

Materials contain charged particles that under the application of external fields respond giving rise to three basic phenomena known as conduction, polarization, and magnetization.


Conduction:

  • Conduction is the phenomenon whereby the free electrons inside the material move under the influence of the externally applied electric field with an average velocity proportional in magnitude to the applied electric field.

  • the conduction current density, is measured in amperes per square meter (A/m2).


JC= σE

  • σ is the conductivity of the material units are Siemens per meter (S/m).

  • J is the current density.


 Polarization:

          Polarization is the phenomenon of creation and net alignment of electric dipoles, formed by the displacements of the centroids of the electron clouds of the nuclei of the atoms within the material, along the direction of an applied electric field.




  • relationship between D and E, which is given by D = εΕ .



  • considering polarization in to account electric flux density is given as D = ε0Ε + P.


ε0 = 8.85* 10-12  (permittivity of free space)

P is the polarization vector or dipole moment per unit volume.

polarization

 Magnetization:

Magnetization is the phenomenon of net alignment of the axes of the magnetic dipoles, formed by the electron orbital and spin motion around the nuclei of the atoms in

the material, along the direction of the applied magnetic field.

  • The relation between the B and H is given as H=B/μ

  • μ is permittivity of material measured in newton per ampere square or Henry per meter.


                                     B= μ0 H + μ0 M

where μ0 = 4π * 10-7, M magnetization vector or magnetic dipole moment

magnetic

 

 

 

 
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