From the symmetry of the problem, we observe that the potential is independent of variation. Similarly, we assume the potential is not a function of z. Thus the Laplace’s equation can be written as

                          ...................................................(2.132)

Integrating the above equation two times we can write

                           .....................................................(2.133)

where C₁ and C₂ are constants, which can be evaluated from the boundary conditions

                         ............................................................(2.134)

Evaluating these constants we can write the expression for the potential as

                         .......................(2.135)