An Overview of Forces between Multiple Charges

Force is the reason behind all phenomena that we observe in the physical world. One of the most well-known types of force is the electrostatic force – a force that governs interactions between the tiniest of entities, electrons in atoms.

The Coulomb force between multiple charges is the foundation for many devices and observations. Understanding how forces operate when there are multiple sources of them is imperative. 

Coulomb’s Law of Electrostatics

Coulomb’s law of electrostatics states that, “The electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects.” 

According to this law, there is an aimed description when two objects play the role of point charges. Coulomb’s law can be represented as an equation:

F= k*Q1*Q2/ d2

In the equation,

F= Electrostatic force

k= proportionality constant

Q1= Quantity of charge on object 1

Q2= Quantity of charge on object 2

d= Distance between the two objects by which they are separated.

The two Qs in the Coulomb’s charge represent the quantities of charge of two objects that are present during interactions. These objects can be either positively or negatively charged. The force value is positive when two Qs are of the same charge and negative when they are of opposite charge. 

Apart from Coulomb’s law of electrostatics, there are other laws proposed by him for charges. According to Coulomb, when charges are of the same kind, they repel. When the charges are of opposite kinds (positive and negative), they attract. 

Significance of Coulomb’s Law

In practice, electrostatic forces and Coulomb’s law of electrostatics work as the determinants for various aspects. These are:

• Coulomb’s law is used for determining mixtures or mixing substances in water. 
• Electrostatic forces play an essential role in the working of Xerox machines. 
• This force is applied to explain phenomena such as balloon sticking to walls, paper sticking to hair, sudden electric charge on touching a human body, etc. 
• The electrostatic force is used for air cleansing through the principles of it. 
• Coulomb’s law of electrostatistics helps in finding how far two objects are from each other. 
• Coulomb’s law of electrostatics is used in calculation of the vector field of two objects in charge. 
• Coulomb’s law of electrostatics determines the inverse square measurement of charged objects. 
• Electrostatic force is exhibited by all types of stationary objects or entities. 

These are the applications and significance of electrostatic forces and Coulomb’s law of electrostatics. 

Limitations of Coulomb’s law:

1. We can use the formula if the charges must be static or stationary to each other.
2. The charge must have a point charge. ( spherically symmetric).
3. The formula is valid only when the solvent molecules between the particles are considerably larger than both the charges.
4. The charge must be a distinct point charge. (they must not overlap)
5. The force depends on the medium where the two charges are kept. 

Superposition Principle 

When a number of charges are interacting, the resultant force on a particular charge is given by the vector sum of the forces produced by the individual charges. 

If several point charges q1, q2 ,  q3….qn simultaneously exert electrical force on the charge, q, then the net force ‘q’ is obtained by taking the vector sum of the individual forces. 

Let us take an example and try to understand this in a better manner. If there are three charges Q1, Q2 and Q3, all in the vicinity of each other, we need to find how the force on a unit charge particle will be when it is close to these three source charges. Electrostatic forces follow the superposition principle. Therefore, if there is more than one force acting on a particle, then the resultant force acting on the particle will be the sum of all these forces. So if a unit charge is placed in between three charges, then the total force on it will be the sum of all the three forces due to the charges.

But force is a vector quantity. Hence the unit charge will get displaced in the direction of the resultant force vector that has a greater magnitude. What this essentially means is if there are just two source charges, A and B, and a unit charge is placed between them, then the charge will move towards the source charge with higher magnitude.

Conclusion

The Coulomb force between multiple charges is the foundation for many devices and observations. Understanding how forces operate when there are multiple sources of them is imperative. 

When a number of charges are interacting, the resultant force on a particular charge is given by the vector sum of the forces produced by the individual charges. 

If several point charges q1, q2 ,  q3….qn simultaneously exert electric force on charge q, then the net force on q is obtained by taking the vector sum of the individual forces.