Homework SourseA point charge q located at x 10 m A second point charge 3q
A point charge +q located at x = 1.0 m. A second point charge -3q is located at X = -1.0 m. 16) Determine the rightward electric field for x 
Solution
16) The electric filed at any point is determined by rule of superposition.
charge +q at x= 1.0 m
charge -3q at x= -1.0 m
for x <-1.0
field due to -3q
E- = 3kq/(-x-1)2 towards right as a unit +ve3 charge would experience force to the right
filed at x due to +q is
E+ = kq/(-x+1)2 towards left
The net right ward field
E = 3kq/(-x-1)2 - kq/(-x+1)2
17) for -1<x<+1
field at x due to -3q
E- = 3kq/(x+1)2 towards right
field at x due to +q
E+ = kq/(1-x)2 to left
net rightward field
E = 3kq/(x+1)2 - kq/(1-x)2
18) for x>+1.0
field at x due to -3q
E- = 3kq/(x+1)2 towards left
field at x due to +q
E+ = kq/(x-1)2 to right
net rightward field
E = kq/(x-1)2 - 3kq/(x+1)2
19) net field is 0
kq/(x-1)2 - 3kq/(x+1)2 =0
(x+1)2 = 3(x-1)2
x2 -4x +1 =0
x= 3.73, 0.27
