**1. The problem statement, all variables and given/known data**
A uniformly charged ring of radius 8.1 cm has a total charge of 118 micro Coulombs. The value of the Coulomb constant is 8.98755e9 N M^2/C^2. Find the magnitude of the

electric field on the axis of the ring at 1.15 cm from the center of the ring. Answer in units of N/C.

**2. Relevant equations**
F= k Qq/ r^2

E= kq/r^2

**3. The attempt at a solution**
I tried subtracting 1.15 cm from 8.1 cm for "r" and plugged that "r" value in the F equation but that answer is wrong. By axis , do they mean horizontally (as in along the diameter) or vertically?Someone said I had to integrate but I dont know what to integrate and from what points.