A BRIEF NOTE ON ELECTRIC DIPOLE

The field of an electric dipole describes the field lines associated when two charges are involved in the case of an electric dipole. The electric field of the dipole at a large distance varies linearly with relation to distance. 

The equal and opposite charges system is separated by a distance commonly known as Electric Dipole. The concept is related to the electric field obtained at large distances due to equal and opposite charges. Electric dipole’s importance and physical significance also enhance the concept’s clarity.

The product of either two charges and the distance between them is the electric dipole moment. The field of an electric dipole is the region around the dipole that can be affected by the dipole’s influence

Electric Dipole: 

• The system consisting of equal and opposite charges separated by a very small distance is called Electric Dipole. 
• Since the charges are present, the field lines will be associated by default, and hence, the direction in space is defined by the lines connecting the two charges. 
• As per convention, the direction of the dipole is taken from –q to +q. 
• Centre Of dipole refers to the midpoint of locations between the two charges. 

The Field of an electric dipole: 

The field of an electric dipole represents the electric field lines witnessed amongst the equal and opposite charges of a dipole. By using Coulomb’s Law and the Superposition principle, one can easily determine the electric field of an electric dipole. The field of an electric field can be determined for two different cases, depending upon the positions of the electric charges placed in space concerning that particular point around which the electric field is to be identified. 

The first step says to note down the point for finding the field lines, i.e., let’s consider any point P across which the effect of charges is felt in the form of field lines. For better understanding, it can be said that we need to determine the intensity of the field of an Electric dipole. Since the dipole system comprises two charges whose magnitude is the same, there will be an electric field denoted by “E” for both a positive charge and a negative charge. 

E(+q) is the electric field due to positive charge (+q), and E(-q) represents the electric field due to the negative charge of an electric dipole. So we will add the electric fields due to positive and negative charge respectively using the very important parallelogram law of vectors, and hence our task of determining the electric field at any general reference point P would be successfully accomplished. 

You might be wondering about the two cases for the intensity of the field of an electric dipole that was mentioned above. Here lies the answer. We will predict the field of an electric for the point P when placed on:-

➢ Axial line of Electric dipole 

➢ Equatorial line of Electric dipole 

Let’s discuss both the cases and the related formulas for the field derived. 

1. The Axial line of an electric dipole:

In this case, the point P is placed on the same axis as the dipole and hence called the Electric Dipole on the Axial Line. Let the distance from the centre of the dipole to the point P be ‘r’ around which the intensity of the electric field is to be calculated. We will have to add the Electric field due to positive and negative charges to get the  Net value of the Electric field associated with the dipole. 

      The electric field for an electric field determined for larger distance (when the r  >>> a), the net field is given as follows: 

|E|=2|p|40r3

Here, the direction of the field on the axial point would be along the axis of the dipole from the negative to positive charge, which is the same as the direction of the p vector, which actually denotes the dipole moment (p=2qa). 

2. Equatorial line of an Electric Dipole:

For calculating the field on the equatorial point, we consider that point P lies on the perpendicular bisector of the dipole, which is ‘r ‘distance away from its centre. 

  Therefore, by Superposition principle, the net associated electric field is given as

Note that here the direction of the field on the Equatorial point would be parallel to the  axis of the dipole from positive charge to negative charge. 

Physical Significance of Electric Dipole:

• A dipole is significant in terms of the dipole moment, which describes the polarity of the molecules like Carbon Dioxide. 
• For example, If the dipole moment of a molecule is zero, one can conclude that the centres of positive and negative charges are at the same place and hence, such molecules are termed as ‘Neutral molecules’.  

Conclusion:

Dipole electric field  is regarded as a very important topic in the field of Physics.  Electrostatics, or the study of energies, fields, and potential outcomes that originate from electrostatic discharge, is the focus of Electric Dipole. A dipole is a pair of charges with the same magnitude but opposite polarity that are separated by a certain distance.The concept is related to the electric field obtained at large distances due to equal and opposite charges. Electric dipole’s importance and physical significance also enhance the concept’s clarity.