An electric dipole is a separation of opposite electrical charges. The electric dipole moment p is the product of any two charges multiplied by the distance between them. Its direction is from a negative to a positive charge. The axis of a dipole is the line that connects the two charges. Assume that the charges of an electric dipole are –q and +q respectively and that they are separated by a modest distance of 2l. Dipole moment is given by p = q x 2l  = 2ql.

The Dipole Moment:

The product of the charge magnitude and the displacement vector going from the negative to the positive charge is the dipole moment. An electric dipole is made up of two opposite-signed charges of equal magnitude. P is the abbreviation for it. The coulomb-metre or debye is the SI unit for dipole moment.

• When the consequences of microscopic charge separation are visible but the actual difference between the charges is too low to measure, the dipole moment can be a helpful notion. Molecules can have constant dipole moments, and atoms and molecules that don’t have one can get such moments by being exposed to an electric field.
• An electric dipole’s potential is computed by adding the potentials of the two-point charges that generate it.
• It provides a measurement of the polarisation of a net neutral system. Either the charges or the spacing is modest if the dipole moment is small. Because of the polarisation, the electric field will be modest as well. The electric field will be non-monopole if the polarisation is large.
• A dipole’s tendency to align with an external electric field is also measured by the dipole moment.

Dipole in Electric Field:

Even though the two electric forces (F=qE) on the charges that act on the dipole endpoints cancel each other as free vectors, they behave as separate points. As a result, a torque is created on the dipole. Furthermore, the dipole experiences a rotational action as a result of the torque.

The components of force perpendicular to the dipole:

Derivation of Torque

Suppose a dipole with charges +q and –q that form a dipole as they are separated by a distance of d. Position it in a homogeneous electric field of E – strength with the dipole’s axis constructing a θ angle with the electric field.

The force on the charges, 

F = ± q E

The components of the force perpendicular to the dipole,

 F = ± q E sinθ

Since the force magnitudes are equal and are separated by a distance, d, the torque on the dipole is:

Torque = Force x distance between forces

τ = (q E sinθ) d = q d E sinθ

Electric Dipole Visualisation:

Assume you have a pair of electric charges of equal magnitude, ‘q’, separated by a distance, d. This structure is known as an electric dipole. As a result, we can say that an electric dipole is generated when equal and opposite charges are separated by a specified distance.

An electric dipole is represented by the symbol, p. An electric dipole is calculated as the force magnitudes are equal and are separated by a distance, d, between them, and it may be expressed mathematically as the following:

The magnitude of an electric dipole is p = qd.

Significance of Electric Dipole and Dipole Moment:

The physical importance of the electric dipole and dipole moment are as follows:

• In their ground state, all atoms are electrically neutral. Atoms have an equivalent amount of opposite charges, as we know. Molecules, like atoms, are neutral, although they have an equal number of positive and negative charges.
• Atoms and molecules make up electrically neutral matter. When the positive charge centre of mass coincides with the negative charge centre of mass, the molecules behave as non-polar molecules. A molecule behaves as a polar molecule when the centre of mass of positive charges somehow doesn’t overlap with that of negative charges.

Permanent dipole moments exist in these polar compounds. In the absence of an external electric field, these dipole moments are arbitrarily directed. When polar molecules are exposed to an external electric field, the molecules align them in the field’s direction. A net dipole moment develops as a result of this. It’s said that this particular piece of material is polarised.

• The study of dipoles yields a polarisation measurement for a net neutral system. Dipole moments are used to measure a dipole’s inclination to align with an external electric field.
• Just because the total of all the charges in a system is zero does not mean that the system’s electric field is zero everywhere. As a result, the research of electric dipoles is critical for understanding electrical phenomena in matter.
• When there is a charge separation, an electric dipole moment occurs. Electrically neutral molecules with ionic compounds or molecules with covalent bonds can both have it. The electric polarity of a system of charges is measured by dipole moments.

Conclusion:

An electric dipole is a charge distribution of a pair of electric charges of equal magnitude and opposite sign. A dipole is a vector determined by the charge distribution’s properties. Two-point charges are considered: q1 at position r1 and q2 at position r2, with opposite signs and equal magnitude. An electric dipole moment is a vector going from a negative electric point charge to a positive electric point charge when both charges are of equal magnitude. The distance between the point charges multiplied by the magnitude of the charges determines the dipole’s size.