# Homework Help: Consider a long cylindrical dielectric shell of inner cross-sectional

1. Jan 4, 2012

### queenstudy

1. The problem statement, all variables and given/known data
consider a long cylindrical dielectric shell of inner cross-sectional radius a , outer radius b, and constant volume charge density raw zero . THe potenials of the ineer and outer surfaces of the cylindrical shell are held at potentials 0 and V respectively as shown in the adjacent figure.
Solve the appropriate boundary value problem and use the given boundary conditions to find the electric potential at any point inside the shell

2. Relevant equations

3. The attempt at a solution
i used poissons equation between a and b is that true or should i also do laplaces equation inside a please reply??

2. Jan 4, 2012

### Gordianus

Re: electromagnetism

Poisson's equation is the right tool for there's a non-zero charge density. Laplace's equation assumes there's no charge

3. Jan 4, 2012

### queenstudy

Re: electromagnetism

i know my friends in the exam solved two equations laplace and poisson i dont know my , but i did only one and got two constants , who do you think is right?? i know that inside the shell is between a and b only right??

4. Jan 4, 2012

### Mindscrape

Re: electromagnetism

Wait, it says that the charge density is zero inside the shell, so you should use laplace. Do separation of variables, obtain your bessel functions etc., and solve for the boundary values.

If it really is poisson you'll have to mess with finding the Green's function that satisfies the potential.

5. Jan 4, 2012

### queenstudy

Re: electromagnetism

i meant raw zero is its name with charge density constant called raw zero, so how many equations am i solving one or two
ps: i couldnt find its symbol my friend mindscrape so i am very sorry