Solution:What is the Electric Field for Two Point Charges on a Line?

[Wildcatfan]

Homework Statement

Consider two point charges placed on a line:

q1=1.00uc_______<2m>_________P_______<2m>________q2=-1.00uc

q1=1.00uc
q2=-1.00uc
r=2m

a) Find the electric field E at the position P *hint: bring + at P. Ep=Ep1+Ep2
b) Using the above E, find the electric force on the charge q=-1.00uc placed at P.
c) Check your answer F of (b) by computing directly F.

Homework Equations

(kq1/r12^2)

The Attempt at a Solution

I attempted to solve and with the charge acting on q1, I got 2.25X10^3 N/C. For the charge acting on q2, I received the answer -2.25X10^3 N/C. I figure this isn't correct since I need to use something other than 0 when these are added to figure out part b. Thanks for your help in advance!

 

[thebigstar25]

:) you are right this is not zero ..

hint : remember that the electric field is a vector , and remember that the electric field produced from a positive charge is not the same as the negatice charge, check this figure:


http://img684.imageshack.us/img684/3059/38165338.jpg



try to draw the electric field vector produced by both the positive and the negative charges , what will you get?