# Homework Help: Potential inside a grounded conducting sphere

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1. Oct 20, 2015

### shinobi20

1. The problem statement, all variables and given/known data
Hi, I'm currently answering a problem in Jackson's electrodynamics. The question is:
Given a point charge q inside a hollow. grounded, conducting sphere of inner radius a. Find the potential inside.

This can be solved by placing an image charge outside the sphere, and placing q a distance say, r from the center. I'm just wondering, what if the charge is exactly at the center of the sphere? What changes in the solution would happen?

2. Relevant equations
Method of Images

3. The attempt at a solution

2. Oct 20, 2015

### BvU

Well, what happens to the image charge if q approaches the center ?

3. Oct 20, 2015

### shinobi20

The image charge approaches infinity. But how will I modify the solution?

4. Oct 20, 2015

### shinobi20

How is the Green function to be used here? I think this is a possible way but I'm not sure.

5. Oct 20, 2015

### BvU

Very good. Now imagine q is distributed over 100 little charges that are evenly distributed on a small spherical shell around the center. That gives 100 image charges evenly distributed very far away, right ?

See where I am going ?

I'm not much good with these (very useful) functions, so I try to wiggle around them