NNSE508_EM-L4_Electrodynamics-1 - 1 Lecture contents...

NNSE 508 EM Lecture #4
1
Lecture contents
• Macroscopic Electrodynamics
– Propagation of EM Waves in dielectrics and metals

NNSE 508 EM Lecture #4
2
• Maxwell equations describing the “coupling” of electric and
magnetic fields
• Interaction with medium: in most simple cases linear isotropic :
• Polarization is linear function of electric field
• Interaction is scalar, local and synchronous
Maxwell Equations
ev
D q  
0 R
D E E     
B
E
t

  

D
H J
t

  

0 B  
1 B
E
c t

  

J
c t
D
c
H
 4 1



  
 4    D
0    B
[SI]
[CGS]
D E  
H B  
J E  
0 R
B H H     
J E  
; 4 P E D E P    
( , ) ( , ) D r t E r t  
Further in this section
the “total” permeability
and permittivity will be
used

NNSE 508 EM Lecture #4
3
Maxwell’s Equations for a Isotropic, Linear, Source -
Free, and Lossless Medium
• Obviously, there must be a source for the
field somewhere.
• However, we are looking at the properties
of waves in a region far from the source.
• Wave equations for electromagnetic
Waves in a Simple, Source-Free, Lossless
Medium
• The wave equations are not independent.
• Usually we solve the electric field wave
equation and determine H from E using
Faraday’s law.
 
 
 
 
2
2
2
2
2
2
E E E
H
E
t
t
H H H
E
H
t
t
 
 
    
 

   


    
 

  


0
0
2
2
2
0
H
H
t


  

2
2
2
0
E
E
t


  


NNSE 508 EM Lecture #4
4
Propagation of electromagnetic waves in an isotropic linear, source-
free, and lossless medium
•