1. 3-6. Conductors in Static Electric Field
Conductors contain free charges.
Inside:
No charge is inside a conductor
No field is inside a conductor.
A conductor is an equal-potential body.
Boundary conditions at a conductor to free space interface
EEE340
Lecture 12

2. Example 3-11. Conductor shell with a point charge at the center
Example Conductor shell with a point charge at the center. Find the and V.
Solution
Gaussian surface S1
i. e.
The potential
EEE340
Lecture 12

3. Inside a conductor. Gaussian surface S2
Note V2 is constant since conductor is an equal potential body.
Inside a conductor.
-Q induced on the inner and +Q on the outer surface of the shell.
EEE340
Lecture 12

4. The integration constant K is found by
Gaussian surface S3
The potential
The integration constant K is found by
Namely
Therefore
EEE340
Lecture 12

5. 3-7. Dielectrics in static E-field
Ideal dielectrics do not contain free charges
They contain bound (polarized) charges
Dielectrics in static E-field produce the induced electric dipoles.
Equivalent charge distributions of polarized dielectrics
Polarization vector
Volume density of electric dipole moment.
EEE340
Lecture 12

6. Potential due to the polarized dielectric
Where
It can be shown
The total charge
EEE340
Lecture 12

7. 3-8. Electric flux density and dielectric constant
Where the electric flux density (displacement)
Electric susceptibility
Relative permittivity (dielectric constant)
Absolute permittivity
EEE340
Lecture 12