Final answer:
The electric field E Ê(z) points along the z-axis in a dipole system, which is determined by the right-hand rule where the positive z-axis corresponds with the direction of E.
Step-by-step explanation:
The question pertains to the direction of an electric field (E) in a system with a dipole. By convention, the electric field points from positive to negative charges. In the scenario described, where E points along one of the primary axes, it points along the z-axis, as given by the notation Ê(z). Additionally, this aligns with the right-hand rule mentioned, where the positive branches of the (x, y, z) axes follow the orientation of the thumb and fingers of the right hand. Therefore, the field E Ê(z) points along the z-axis.