A ring-shaped conductor with radius a=.029 m has a total positive charge Q=1.35x10^-9 C uniformly distributed around it. The center of the ring is at the origin. What is the electric field at point P, which is on the axis at x=.3m? I used the equation E=(kQx)/(x^2+a^2)^3/2, but this doesn't seem to work. Many thanks if you could help me!