1. The problem statement, all variables and given/known data Find the force acting on an electron located "d" distance from the midpoint of a line of charge, length "L", located on the x axis. The line of charge is positive. 2. Relevant equations F(e)=kq1q2/r^2 3. The attempt at a solution λ=linear density, here the charge is uniform. So, dq=λdx I think? The distance is the variable that is changing, so we should integrate the dx and the limits should be over the length of the line? k, e(electron) and λ are constant and can be brought out of integral... if the origin is the midpoint, then the limits of integration are -L/2 to L/2? The solution the book gives is the following: 4keλL/(4d^2-L^2) I don't know where I'm going wrong with this equation, maybe I have the wrong r value? Is r=(d-x)^2 when dx is along the positive x axis? Any tips or perspectives would be great!