Consider a charged ring of radius 43.4 cm and total charge 18 nC.

Question

We are interested in the electric field a perpendicular distance z away from the center of the ring.

At what distance from the center of the ring does the electric field become maximum?

Answer 1

http://www.ac.wwu.edu/~vawter/PhysicsNet/Topics/ElectricForce/Axis-of-Loop.html