Question

A point charge Q1 = + 3 C is placed at the origin, and a point charge Q2 = -7 C is placed at x = 0.4 m on the x-axis of a Cartesian coordinate system.
(a) Determine the electric field, , at all points along the x-axis.
(b) Plot E(x) vs. x for x  0.

Answer 1

Electric field is calculated by $E=\dfrac{kq}{r^2}$

so in the the region in between the two two point charges the the electric field will be always directed towards the positive x

in the region x>0.4 the electric field will be always in the negative x as |Q2|>|Q1|