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The electric charge is all about us, and there is plenty of evidence to back this up. Have you ever lifted a comb to your hair after rubbing it through a towel? That section of your hair will be pulled to the comb. This is primarily concerned with the generation of electrical charge. In this part, we’ll try to deduce how opposing charges behave when held at a distance. This is the concept of the Electric Dipole, which is a crucial aspect of electrostatics.
What is an Electric Dipole?
An electric dipole is a persistent dipole with equal and contrary charges divided by a huge area. The initial charge should be minus (-q), whereas the second charge should be positive (-p) (q). Electric dipoles in space are typically targeted from negative charge ‘-q’ to positive charge ‘q’ by default. The dipole’s centre is where the letters ‘q’ and ‘-q’ meet.
What is the Electric Dipole Moment?
It’s essentially a precise measurement of an electric dipole’s strength. The magnitude of the generated dipole moment is the product of either charge and the distance of separation ‘d’ between them, according to mathematics and scientific investigations. Remember that the dipole moment is a vector measurement with a negative to positive charge direction.
Electric Potential Due to Dipole
Assume that a dipole is generated by two charges separated by d, –q at A and +q at B. Assume that O is the AB’s midpoint.
The electric potential associated with a dipole at every point P where OP = r is:
V is equal to (1 ⁄ 4 π ε) (p cosθ ⁄ r2)
where,
- The electric potential is V.
- The electric dipole moment is denoted by p.
- r is the distance between two possible points, and
- θ is the angle that the dipole makes with the point.
Case I: For θ = 0°, V = (1 ⁄ 4 π ε) (p ⁄ r2)
Case II: For θ = 90°, V = 0
Dipole Placed in an Electric Field
The two forces operating on the dipole ends cancel each other as free vectors, yet they work as independent points. A torque is formed on the dipole as a result. Furthermore, as a result of the torque, the dipole spins.
In the presence of an electric field, consider an electric dipole. The electric dipole will experience torque, which is a force applied to it. The torque is the force exerted on dipoles in the presence of an external field, and it is calculated as follows:
τ is equal to p × E
or
τ is equal to p E sinθ
where,
- τ can be defined as the torque on dipole,
- E refers to the electric field, &
- θ denotes the angle between dipole and electric field.
Physical Significance of Dipole
Not only is the theory of an electric dipole vital in physics, but it is also a valid and significant topic in chemistry.
Because most materials are made up of atoms and molecules, we know that they are electrically neutral. The behaviour of the pair of charges is used to divide the molecules into two categories.
Polar Molecule: A polar molecule is the one in which the centre of mass of the positive charge does not match the centre of mass of the negative charge.
Non-Polar molecules: The centre of mass of the positive charge corresponds to the centre of mass of the negative charge in a nonpolar molecule.
Polar compounds have permanent dipole moments. These dipoles are oriented randomly in the absence of an external electric field. The polar molecules align themselves in the direction of the electric field when it is applied.
If a system’s net charge is zero, that doesn’t mean there won’t be an electric field or that the dipole won’t be there. This was demonstrated using the electric dipole moment. As a result, learning how to investigate an electric dipole is essential. Understanding polarisation aids our understanding of dipoles and dipole moments.
What is The Direction of The Dipole?
A pair of equal and opposing point charges q and -q separated by a distance d from an electrical dipole.
The direction of the dipole is defined as the direction from negative to positive charge by convention.
Conclusion
Most molecules have both positive and negative charge centres in the same place. As a result, they have no dipole moment. This class of molecule includes CO2 and CH4. They form a dipole moment when an external magnetic field is applied. However, in some compounds, the centres of negative and positive charges may not always overlap. As a result, they exhibit a constant electric dipole moment even in the absence of an electric field.
Polar molecules are the name for these types of the permanent dipole. H2O molecules, for example, are an example of this type. In the presence or absence of an electric field, some materials exhibit fascinating properties and have vital applications.
