College Physics 10th Edition by Raymond Serway,Chris Vuille

Exercise 20

A point charge of magnitude 5.00 C is at the origin of a coordinate system, and a charge of 4.00 C is at the point x = 1.00 m. There is a point on the x -axis, at x less than infinity, where the electric field goes to zero. (a) Show by conceptual arguments that this point cannot be located between the charges. (b) Show by conceptual arguments that the point cannot be at any location between x = 0 and negative infinity. (c) Show by conceptual arguments that the point must be between x = 1.00 m and x = positive infinity. (d) Use the values given to find the point and show that it is consistent with your conceptual argument.