Several companies produce personal water filters that can travel anywhere. Such filters make any water safe to drink by removing bacteria and other contaminants. However, they cannot filter heavy metals and viruses or remove salt. The filters are constructed of sturdy plastic and weigh just two ounces. They can be purchased in stores or online for about $20. Evaluate this design by describing the criteria it does or does not meet.

Athin nonconducting rod with a uniform distribution of positive charge q is bent into a circle of radius r. the central perpendicular axis through the ring is a z-axis, with the origin at the center of the ring. a) what is the magnitude of the electric field due to the rod at z = 0? n/c (b) what is the magnitude of the electric field due to the rod at z = infinity? n/c (c) in terms of r, at what positive value of z is that magnitude maximum? r (d) if r = 4.00 cm and q = 9.00 µc, what is the maximum magnitude? n/c