Exercise 1.  Find the electrostatic potential  [Graphics:Images/ElectrostaticsModHome_gr_1.gif]  between the two coaxial cylinders  [Graphics:Images/ElectrostaticsModHome_gr_2.gif]  and  [Graphics:Images/ElectrostaticsModHome_gr_3.gif],  

that has the boundary values,  (shown in Figure 11.39)    

                    [Graphics:Images/ElectrostaticsModHome_gr_4.gif]  

Solution 1.

See text and/or instructor's solution manual.

Answer.   [Graphics:../Images/ElectrostaticsModHome_gr_5.gif].  

Solution.   Applying Example 11.3 in Section 11.1 we know that the form of the solution is  

                    [Graphics:../Images/ElectrostaticsModHome_gr_6.gif].  

Substitute   [Graphics:../Images/ElectrostaticsModHome_gr_7.gif]   and get    

                    [Graphics:../Images/ElectrostaticsModHome_gr_8.gif]  

Therefore,   

                    [Graphics:../Images/ElectrostaticsModHome_gr_9.gif].   

 

We are done.   

 

Aside.  We can let Mathematica double check our work.

[Graphics:../Images/ElectrostaticsModHome_gr_10.gif]

[Graphics:../Images/ElectrostaticsModHome_gr_11.gif]

Aside.   If polar coordinates   [Graphics:../Images/ElectrostaticsModHome_gr_12.gif]   are used, then the polar form of the solution is     

                    [Graphics:../Images/ElectrostaticsModHome_gr_13.gif].   

[Graphics:../Images/ElectrostaticsModHome_gr_14.gif]

[Graphics:../Images/ElectrostaticsModHome_gr_15.gif]

We are really done.   

 

Aside.  For illustration purposes we can graph the function   [Graphics:../Images/ElectrostaticsModHome_gr_16.gif].   

                     [Graphics:../Images/ElectrostaticsModHome_gr_17.gif]

                     A contour graph of the function   [Graphics:../Images/ElectrostaticsModHome_gr_18.gif]

                     where   [Graphics:../Images/ElectrostaticsModHome_gr_19.gif]   for   [Graphics:../Images/ElectrostaticsModHome_gr_20.gif].  

 

We are really really done.   

 

                     [Graphics:../Images/ElectrostaticsModHome_gr_21.gif]

                     A contour graph of the function   [Graphics:../Images/ElectrostaticsModHome_gr_22.gif]

                     where   [Graphics:../Images/ElectrostaticsModHome_gr_23.gif]   for   [Graphics:../Images/ElectrostaticsModHome_gr_24.gif].  

 

                     [Graphics:../Images/ElectrostaticsModHome_gr_25.gif]

                    A graph of the function   [Graphics:../Images/ElectrostaticsModHome_gr_26.gif],    

                    [Graphics:../Images/ElectrostaticsModHome_gr_27.gif]  

                     [Graphics:../Images/ElectrostaticsModHome_gr_28.gif]

                    A graph of the function   [Graphics:../Images/ElectrostaticsModHome_gr_29.gif],    

                    [Graphics:../Images/ElectrostaticsModHome_gr_30.gif]   

                     [Graphics:../Images/ElectrostaticsModHome_gr_31.gif]

                    A graph of the function   [Graphics:../Images/ElectrostaticsModHome_gr_32.gif],  

                    [Graphics:../Images/ElectrostaticsModHome_gr_33.gif]   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

This solution is complements of the authors.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2008 John H. Mathews, Russell W. Howell