Two rings carry uniformly distributed charges, one of +25 nC and the other of -25 nC. They are placed

Question

16 cm apart, concentric with a common horizontal axis. The ring on the left carries the positive
charge and the one on the right negative charge. Each ring has a radius of 5.0 cm. Determine the
electric field on the horizontal axis, halfway between the two rings.

Answer 1

radius = 0.05meters, that is distance all charges are off axis
so distance from center of hor axis to charges = d = sqrt (0.05^2 + 0.08^2)
but use only the axial component so charge * cos (.08 )/ d
so 2 * Q * cos (0.08/d) * k / d^2

Answer 2

whoops, used cos twice

so charge * (.08 )/ d
so 2 * Q * (0.08/d) * k / d^2

Answer 3

cos my hol.
use arctan