[SOLVED] Calculate Electric field from two point charges 1. The problem statement, all variables and given/known data Two point charges with q1=2x10^-5 and q2=-4x1-^-3 are located in free space at (1,3,-1) and (-3,1,-2), respectively, in a cartesian coordinate system. Calculate the electric field E at (3,1,-2) 2. Relevant equations E=(1/4piE0)(-qr1/r1^3+qr2/r2^3) 3. The attempt at a solution I understand the above equation but am unsure of how to implement it using cartesian coords?