# [SOLVED] Calculate Electric field from two point charges

by mikehibbert
Tags: charges, electric, field, point, solved
 P: 37 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?
 Emeritus Sci Advisor PF Gold P: 4,975 The distance between two points is: $$s = \sqrt{(x_1-x_2)^2+(y_1-y_2)^2+(z_1-z_2)^2}$$
 P: 37 how do i use the vector in this part of the equation though? q1r1/r1^3 the r1 on top is still a vector... and then i presume for the bottom part i just take the magnitude of r1 and cube it?
Emeritus
 Emeritus Sci Advisor PF Gold P: 4,975 Make that: $((x_1-x_2) \mathbf{\hat{i}}+.....)$ etc.