
#1
Jan2508, 12:30 PM

P: 11

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 xy 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 zaxis 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. 



#2
Jan2508, 12:54 PM

P: 2,048

Well, for one, you haven't taken into account the charge of the electron  it's magnitude to be precise. The question asks you to find the force F = qE, where q is the charge of the test particle.
Secondly, you don't have the right unit for force. 



#3
Jan2508, 05:49 PM

P: 11

Thanks for the help.



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