(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

We have a sphere with radius b, within that sphere there's another sphere with radius a. Between the two spheres we have an electric charge with density A/r. Also, we have a charge Q in the center. We need to find the constant A so that the field between a and b is independent of r (meaning, it's constant for a<=r<=b).

2. Relevant equations

Gauss' law.

3. The attempt at a solution

I added the scanned pages I've written, it should be understandable. As I said, I used Gauss' law to calculate the field, using a sphere with radius r (a<=r<=b) to calculate the electric flux. After finding the electric field as a function of r, I calculated d(E(r))/dr and demanded that it would be=0, but I can't seem to get a solution for A that's independent of r.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Electric field calculation

**Physics Forums | Science Articles, Homework Help, Discussion**