4. A circular are of radius R lies in the zy plane with center of curvature on the z axis. The arc has uniform linear charge density λ on it. a. Find the electric field at a position z on the z axis above the arc ("out of the page" as seen here). b. Show that when the are becomes a complete circle, the electric field be- comes E XR=2 260 (R² +22)3/2

4. A circular are of radius R lies in the zy plane with center of curvature on the z axis. The arc has uniform linear charge density λ on it. a. Find the electric field at a position z on the z axis above the arc ("out of the page" as seen here). b. Show that when the are becomes a complete circle, the electric field be- comes E XR=2 260 (R² +22)3/2