Final answer:
The resultant electric field of two charges positioned on the x-axis can be zero at a point between them if they are of equal magnitude and opposite sign. The specific point on the x-axis where this occurs depends on the symmetry and magnitude of the charges.
Step-by-step explanation:
The question is asking about the point on the x-axis where the resultant electric field of two charges is zero, other than at infinity. For two charges on the x-axis, there can be a point between them where the electric fields cancel each other out, assuming the charges are of equal magnitude and opposite sign. The exact location depends on the positions and magnitudes of the charges. If the charges are of equal magnitude and opposite sign and placed symmetrically around the origin, the electric field will be zero at the origin. This is because the electric field vectors point towards negative charges and away from positive charges, and at the midpoint, these fields will have the same magnitude but opposite directions, canceling each other out.
For charges that are not symmetrically positioned, or if their magnitudes are not equal, the point of zero electric field will not be at the midpoint but can still exist along the axis at some other position. Since electric field lines must begin on positive charges and end on negative charges, the principle of superposition allows us to determine the net electric field by considering the electric field contribution from each charge separately. The net flux through a surface can also be computed using the principle of superposition and by making symmetry arguments.