Bound and Free Charge in conductor and dielectric

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SUMMARY

The discussion focuses on the distinction between bound and free charges in conductors and dielectrics, emphasizing that free charges can move freely in response to external forces, while bound charges are limited to small movements around their respective atoms or molecules. A specific example is provided regarding a wire carrying charge Q, insulated by a dielectric, where the bound charges on the inner and outer surfaces of the insulator are equal in magnitude. The user seeks clarification on applying Gauss's law for electric displacement (D) to derive the relationship between bound charge density (ρb) and free charge density (ρf), specifically the equation ρ = ρb + ρf.

PREREQUISITES
  • Understanding of electrodynamics principles
  • Familiarity with Gauss's law for electric displacement (D)
  • Knowledge of charge density concepts (bound and free charge)
  • Basic comprehension of conductors and dielectrics
NEXT STEPS
  • Study the application of Gauss's law in electrostatics
  • Explore the concept of electric displacement field (D) in dielectrics
  • Learn about the relationship between bound charge density and free charge density
  • Investigate the behavior of charges in different dielectric materials
USEFUL FOR

Students and professionals in physics, particularly those studying electrodynamics, electrical engineers, and anyone seeking to deepen their understanding of charge behavior in conductors and dielectrics.

FourierX
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I am reading an electrodynamics book to grasp the concept of bound and free charge, esp in conductor and dielectric. I got lost with the text on the book. Can anyone please help me understand the concept well?
 
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I bet some people here could help... what specific questions do you have?
 
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A free charge can move in response to an externally supplied force while a bound charge cannot.
 
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Free charges are free to move about the entire medium, while bound charges are restricted to moving in small 'loops' around whichever molecule/ atom they are bound to.
 
gabbagabbahey said:
Free charges are free to move about the entire medium, while bound charges are restricted to moving in small 'loops' around whichever molecule/ atom they are bound to.

For a bit more detail, click free charge for the PF Library item :smile:
 
thanks

in case of a wire carrying a certain amount of charge, say Q, which is insulated by a insulator (dielectric), I read that the bound charge on the outer surface and inner surface of the insulator is equal to each other in magnitude. But I could not derive it myself. My approach was to use Gauss's law for D, but i did not get what enclosed free charge was. In such a case, how does the equation \rho = \rhob + \rhof hold true?
 

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