1. The problem statement, all variables and given/known data A small disc or radius R with surface normal ˆ k is placed a distance z from a point charge −q,( k hat pointing along the z-axis which goes through the charge and the center of the disk.) Assuming that R ≪ z, derive an expression for the electric ﬂux ΦE passing through the disc. Hint: Think of the correct approximation to make before starting the question. 2. Relevant equations ΦE= q/ε 3. The attempt at a solution I'm struggling to think of the approximation to simplify this problem. I can only think that with z much greater than R the disk would be a point charge but that wouldn't help at all. Any help to get started on the problem would be appreciated.