Demonstration of an Electric Dipole
A wooden dowel rod (non conductor) is balanced on a sharp needle and placed between a pair of parallel plates connected to an electrostatic generator. When the plates are charged, the dowel rod aligns itself along the E–field, which is perpendicular to the faces of the plates.
An electric dipole is two charged objects, with equal but opposite electric charges, that are separated by a distance.
The electric field caused by a dipole falls off as the cube (third power) of the distance from the dipole, and has a directional variation that depends on whether you're moving along the line separating the two charges or perpendicular to it.
A dipole can be created, for example, when you place a neutral atom in an electric field, because the positively–charged constituents of the atom will be pulled one way, and the negatively–charged constituents the other way, creating a separation of charge in the direction of the field. In simple terms Dipole is a pair of point charges with equal magnitude and opposite in sign separated by a distance.
Many physical systems from molecules to TV antenna can be described as electric dipoles. A water molecule is an example of an electric dipole. Even though the water molecule as such is neutral, the chemical bonds within the molecule causes displacement of charges. This displacement of charges creates a dipole with a negative charge on the oxygen end and a net positive charge on the hydrogen end. Molecules such as HCl, CO and H2O have permanent dipoles and are called polar molecules. An electric field may also induce a charge separation in an atom or a non–polar molecules
Electric dipole moment is represented by a vector p of magnitude 2qa and this vector points in direction from –q to +q. potential due to electric dipole is inversely proportional to r2 not ad 1/r which is the case for potential due to single charge. Potential due to electric dipole does not only depends on r but also depends on angle between position vector r and dipole moment p.