Posted by Andrew on Thursday, February 3, 2011 at 4:59am.
1) Charges of +4uC and 6uC are placed at two corners of an equilateral triangle with sides of 0.10m. At the third corner, what is the electric field magnitude created by these two charges?
A]4.5 x 10e6 N/C
B]3.1 x 10e6 N/C
C]1.6 x 10e6
D]4.8 x 10e6
2)A +2.0 nC pont ahrge isplaced at one corner of a square (1.5m on each side), and a 3.0 nC charge is placed on a corner diagonally away from the first charge. What is the magnitude of the electric fled at either the two unoccupied corners?
A]20 N/C
B]14 N/C
C]4 N/C
D]12 N/C
E]8 N/C

Physics  drwls, Thursday, February 3, 2011 at 6:07am
Both problems involve the adding of two vectors. Get the magnitude of each vector using Coulomb's law.
You should make an effort to do these yourself.
In problem 2), you end up adding two perpendicular Efield vectors with magnitudes
k*2*10^9/(1.5)^2 and
k*3*10^9/(1.5)^2
The magnitude is, from the Pythagorean Theorem,
(k/2.25)*10^9 sqrt13
Using 9.0*10^9 for k, I get 14.4 N/C 
Physics  Anonymous, Friday, October 3, 2014 at 5:00am
4.8 x 10^6 N/C