At a point on the axis of an electric dipole

It seems like your question is incomplete. However, I can tell you that at any point on the axis of an electric dipole, the electric field is given by the formula:

E = 1/4πε * (2p/r³)

Where:

• E is the electric field
• ε is the permittivity of free space
• p is the dipole moment
• r is the distance from the center of the dipole

This formula tells us that the electric field along the axis of a dipole decreases with the cube of the distance from the center of the dipole. It also tells us that the electric field is directed away from the dipole if the dipole moment is positive, and towards the dipole if the dipole moment is negative.