(You can see the figure in that article). Molecules that have a dipole moment will orient in an electric field. Based on scientific and mathematical conclusions, the dipole moment magnitude is the product of either of the charges and the separation distance (d) between them. In classical electromagnetism, polarization density (or electric polarization, or simply polarization) is the vector field that expresses the density of permanent or induced electric dipole moments in a dielectric material. Let us derive the relation between polarization vector (P), displacement (D) and electric field (E): In the last article of polarization, we have discussed about the effect on dielectric placed in an external electric field E 0 and there will be electric field due to polarized charges, this field is called electric field due to polarization (E p). where p ^ is the electric dipole moment unit vector from –q to +q. Since the electric dipole moment vector is from –q to +q and is directed along BC, the above equation is rewritten as. The orientation of magnetic induction vectors varies accordingly. The electric dipole moment for a pair of opposite charges of magnitude q is defined as the magnitude of the charge times the distance between them and the defined direction is toward the positive charge. When a dielectric is placed in an external electric field, its molecules gain electric dipole moment and the dielectric is said to be polarized. If placed in a uniform E-field , there would be a torque on the dipole. Consi der an electric dipole AB consisting of +q and -q charges separated by a distance 2l . Applications involve the electric field of a dipole and the energy of a dipole when placed in an electric field. The line perpendicular to the axial line and passes through the centre of the electric dipole length is called an equatorial line. Let’s take an arrangement for charges viz: electric dipole, and consider any point on the dipole. The dipole moment is particularly useful in the context of an overall neutral system of charges, for example a pair of opposite charges, or a neutral conductor in a uniform electric field. This is a vector. Electric Field due to Dipole at any Point. Dipole field: For such a system of charges, visualized as an array of paired opposite charges, the relation for electric dipole moment is: These are known as second order non-linear materials. The direction of the dipole moment is the direction of the electric field coming out from the +ve end. Let there be a system of two charges bearing + q and - q charges separated by some distance ‘2a’, and how to calculate the electric field of a dipole. Relation between the displacement of elecric charges creating an electric dipole mo-ment and the current in a loop producing a magnetic moment meridians, while that of the current loop is directed perpendicularly to the meridional planes along the parallels. The electric field at a point C due to … Do remember that, the dipole moment is a vector measure whose direction runs from negative to a positive charge. The force that is on the system is a torque that is related to angle between dipole and the electric field, and upon the magnitude of the field and the dipole. So in quantum theory, typically the interaction between a photon and an atom is described by the following interaction term in the Hamiltonian: \begin{equation} H_{\text{int}} = e \mathbf{E}\cdot \mathbf{d}_e \end{equation} where $\mathbf{d}_e$ is the electric dipole moment of the atom and $\mathbf{E}$ is the incident photon electric field. To start with, the characteristic of an electric dipole is its dipole moment. The electric field at a point C due to +q is.