[SOLVED] Electric Field Produced by a Ring 1. The problem statement, all variables and given/known data A uniform circular ring of charge Q=5.60microCoulombs and radius R=1.30 cm is located in the x-y plane, centered on the origin as shown in the figure. If z is much smaller than R then E is proportional to z. (You should verify this by taking the limit of your expression for E for z much smaller than R.) If you place an electron on the z-axis near the origin it experiences a force Fz=-Az, where A is a constant. Obtain a numerical value for A. 2. Relevant equations Ez= (kQz)/(R^2+z^2)^(3/2) 3. The attempt at a solution Since R is much greater than z and the electron carries a minus sign, Ez simplifies to (-kQz)/(R^3) Then Eqauting Fz and Ez gives (-kQz)/(R^3)=(-)Az which then simplifies to (kQ)/(R^3)=A Plugging in the numbers gives (9*10^9*5.6*10^-6 C)/(.013 m)^3= 2.3*10^10 kg/s^2 What am I doing incorrectly? Any help is appreciated.