1. The problem statement, all variables and given/known data A Ring with center in (0,0) and R radius. The charge distribution from the ring is: ψ(θ) = ψo*Sin(θ), where θ is the angle from the x axis (counterclowise). Negative values of the sine determine negative charge, and 0 no charge at all. What is the field (E) created from this distribution (only x and y components)? 2. Relevant equations If there we introduce a constant eletric field, F, in the positive direction of the y axis. How can i find the equipotentials lines from the sum of the fields? 3. The attempt at a solution I tried to find the dEx and dEx as a function of dθ, so i could integrate from 0 to 2*π and get the field vector as function of x and y. I found: dEx = K*ψ(θ)*[x-R*Cos(θ)]*dθ/[ (y-R*Sin(θ))2+(x-R*Cos(θ))2 ]3/2 dEy = K*ψ(θ)*[y-R*Sin(θ)]*dθ/[ (y-R*Sin(θ))2+(x-R*Cos(θ))2 ]3/2 where K = 1/(4*π*εo) or about 9*10^9 N*m2*C-2 But when i calculate the integration i get 0 for both. Any ideas? I can add a picture later, i can't now.