Consider waves in different media.
By using Ohm's Law
The Ampere's law can be expressed as:
Define
, the Ampere's law can be reduced to
The Faraday's law is
Consider a plane wave solution
,where
Skin Depth, Penetration Depth, Plasma Frequency
Editor:鐘國峰、林光威、黃智猷
Advisor:江簡富教授
Wave In Media
Consider waves in different media.
By using Ohm's Law
The Ampere's law can be expressed as:
Define , the Ampere's law can be reduced to
The Faraday's law is
Consider a plane wave solution,
where
(1)If the medium is copper, 
, and the wave number can be approximated as
, 
The time variation of electric field becomes
If 
(2)If the medium is ice , the wave number can be approximated as
where 
and 
The time variation of electric field becomes
If 
thus 
and we let it be k1.
and we let it be k2.
(3)In the ionosphere, charges follow the Newton's law:
Let 
then the equation of motion becomes
,
Since 
, the Ampere's law can be expressed as
where 
is the plasma frequency.
Consider a plane wave solution 
We have 
The time variation of electric field becomes
, 
, 
If 
,?
we find plasma frequency
(a) 
and choose x-axis to be ‘z/
’
(b) 
and choose x-axis to be ‘z/
’