1. The problem statement, all variables and given/known data Consider a charge density of ρ=k/r , k>0 , located between a sphere surface of r=a and another sphere surface of r=b, b>a. I'm supposed to find the electric field on all space, which I did. Now I have to find the electric potential in all space, which I also did for r>b, but I'm having problems finding it for a<r<b and for r<a. 2. Relevant equations These are the electric field equations I came up with: r<a : E(r)=0 r>b: E(r)=(k*(b2-a2))/(ε0*2*r2) a<r<b: E(r)=(k*(1-a2/r2))/(2*ε0) Electric potential for r>b: V(r)=(b2-a2)/(2ε0*r) 3. The attempt at a solution For finding the EP at r>b I just had to integrate E(r) for r>b with limits between r and ∞ which is equal to V(r)-V(∞) with V(∞)=0, but I cant come up with any solution for the other Epotentials, if someone could give me a hint I would appreciate. Thanks!