using
 |
(9.43) |
 |
(9.44) |
Combining equations (9.43) and (9.44) we get,
From equation (9.40) we have
 |
(9.45) |
Thus we get ψm2 as
Substituting this value of ψm2 in (9.32), we get
 |
(9.46) |
This equation is valid only for small potentials. It must be noted that value of FR could positive or negative for same type of potential. Thus FR could be attractive or repulsive same type of potential, depending upon the values of ψo1 and ψo2. However FR will always be attractive for different type of potential on the surfaces. Energy per unit area when 2 charged surfaces are brought from infinity to separation distance can be calculated as:
 |
(9.47) |
|
