# Homework Help: Average electric field in spherical volume

1. Apr 21, 2010

### jam357

1. The problem statement, all variables and given/known data

Show that the average electric field within a spherical region, due to a single point charge, q at a distance r from the center, within the sphere is the same as the field at r due to a uniformly charged sphere with charge density p = -3q/4pi(R^3)

2. Relevant equations

3. The attempt at a solution

I can set up the integral for the average electric field, but run into problems when trying to evaluate it. I don't know whether there is a better way to tackle this problem, but i would appreciate any advice on how to tackle this problem.
This is a problem out of Griffiths Intro to Electrodynamics, problem 3.41
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Apr 21, 2010

### gabbagabbahey

Direct integration is the only way, so show us the integral you've come up with.

3. Apr 23, 2010

### jam357

The integral is not particularly nice, but i found a more cunning way to solve the problem, but thanks anyway. I also don't know how to write mathematical expressions on this thing